ovn-sb(5)                     Open vSwitch Manual                    ovn-sb(5)

NAME
       ovn-sb - OVN_Southbound database schema

       This  database  holds  logical and physical configuration and state for
       the Open Virtual Network (OVN) system to support  virtual  network  ab‐
       straction. For an introduction to OVN, please see ovn-architecture(7).

       The OVN Southbound database sits at the center of the OVN architecture.
       It is the one component that speaks both southbound directly to all the
       hypervisors  and  gateways, via ovn-controller/ovn-controller-vtep, and
       northbound to the Cloud Management System, via ovn-northd:

   Database Structure
       The OVN Southbound database contains classes  of  data  with  different
       properties, as described in the sections below.

     Physical network

       Physical  network tables contain information about the chassis nodes in
       the system. This contains all the information  necessary  to  wire  the
       overlay,  such  as  IP  addresses, supported tunnel types, and security
       keys.

       The amount of physical network data is small (O(n)  in  the  number  of
       chassis)  and it changes infrequently, so it can be replicated to every
       chassis.

       The Chassis and Encap tables are the physical network tables.

     Logical Network

       Logical network tables contain the topology  of  logical  switches  and
       routers,  ACLs,  firewall  rules, and everything needed to describe how
       packets traverse a logical network,  represented  as  logical  datapath
       flows (see Logical Datapath Flows, below).

       Logical network data may be large (O(n) in the number of logical ports,
       ACL rules, etc.). Thus, to improve scaling, each chassis should receive
       only  data  related  to logical networks in which that chassis partici‐
       pates.

       The logical network data is ultimately controlled by the cloud  manage‐
       ment  system  (CMS)  running northbound of OVN. That CMS determines the
       entire OVN logical configuration and therefore the logical network data
       at any given time is a deterministic function of the  CMS’s  configura‐
       tion,  although that happens indirectly via the OVN_Northbound database
       and ovn-northd.

       Logical network data is likely to change  more  quickly  than  physical
       network  data. This is especially true in a container environment where
       containers are created  and  destroyed  (and  therefore  added  to  and
       deleted from logical switches) quickly.

       The    Logical_Flow,    Multicast_Group,   Address_Set,   DHCP_Options,
       DHCPv6_Options, and DNS tables contain logical network data.

     Logical-physical bindings

       These tables link logical and physical components. They show  the  cur‐
       rent  placement of logical components (such as VMs and VIFs) onto chas‐
       sis, and map logical entities to the values that represent them in tun‐
       nel encapsulations.

       These tables change frequently, at least every time a VM powers  up  or
       down  or  migrates,  and especially quickly in a container environment.
       The amount of data per VM (or VIF) is small.

       Each chassis is authoritative about the VMs and VIFs that it  hosts  at
       any  given time and can efficiently flood that state to a central loca‐
       tion, so the consistency needs are minimal.

       The Port_Binding and Datapath_Binding tables contain binding data.

     MAC bindings

       The MAC_Binding table tracks the bindings from IP addresses to Ethernet
       addresses that are dynamically discovered  using  ARP  (for  IPv4)  and
       neighbor  discovery (for IPv6). Usually, IP-to-MAC bindings for virtual
       machines are statically  populated  into  the  Port_Binding  table,  so
       MAC_Binding  is  primarily  used  to discover bindings on physical net‐
       works.

   Common Columns
       Some tables contain a special column named  external_ids.  This  column
       has  the  same  form  and purpose each place that it appears, so we de‐
       scribe it here to save space later.

              external_ids: map of string-string pairs
                     Key-value pairs for use by the software that manages  the
                     OVN   Southbound   database   rather   than  by  ovn-con‐‐
                     troller/ovn-controller-vtep.  In  particular,  ovn-northd
                     can use key-value pairs in this column to relate entities
                     in the southbound database to higher-level entities (such
                     as  entities  in the OVN Northbound database). Individual
                     key-value pairs in this column may be documented in  some
                     cases  to  aid  in understanding and troubleshooting, but
                     the reader should not mistake such documentation as  com‐
                     prehensive.

TABLE SUMMARY
       The  following list summarizes the purpose of each of the tables in the
       OVN_Southbound database.  Each table is described in more detail  on  a
       later page.

       Table     Purpose
       SB_Global Southbound configuration
       Chassis   Physical Network Hypervisor and Gateway Information
       Chassis_Private
                 Chassis Private
       Encap     Encapsulation Types
       Address_Set
                 Address Sets
       Port_Group
                 Port Groups
       Logical_Flow
                 Logical Network Flows
       Logical_DP_Group
                 Logical Datapath Groups
       Multicast_Group
                 Logical Port Multicast Groups
       Mirror    Mirror Entry
       Meter     Meter entry
       Meter_Band
                 Band for meter entries
       Datapath_Binding
                 Physical-Logical Datapath Bindings
       Port_Binding
                 Physical-Logical Port Bindings
       MAC_Binding
                 IP to MAC bindings
       DHCP_Options
                 DHCP Options supported by native OVN DHCP
       DHCPv6_Options
                 DHCPv6 Options supported by native OVN DHCPv6
       Connection
                 OVSDB client connections.
       SSL       SSL configuration.
       DNS       Native DNS resolution
       RBAC_Role RBAC_Role configuration.
       RBAC_Permission
                 RBAC_Permission configuration.
       Gateway_Chassis
                 Gateway_Chassis configuration.
       HA_Chassis
                 HA_Chassis configuration.
       HA_Chassis_Group
                 HA_Chassis_Group configuration.
       Controller_Event
                 Controller Event table
       IP_Multicast
                 IP_Multicast configuration.
       IGMP_Group
                 IGMP_Group configuration.
       Service_Monitor
                 Service_Monitor configuration.
       Load_Balancer
                 Load_Balancer configuration.
       BFD       BFD configuration.
       FDB       Port to MAC bindings
       Static_MAC_Binding
                 IP to MAC bindings
       Chassis_Template_Var
                 Chassis_Template_Var configuration.
       Advertised_Route
                 Advertised_Route configuration.
       Learned_Route
                 Learned_Route configuration.
       ECMP_Nexthop
                 ECMP_Nexthop configuration.
       ACL_ID    ACL_ID configuration.
       Advertised_MAC_Binding
                 Advertised_MAC_Binding configuration.

SB_Global TABLE
       Southbound  configuration  for  an OVN system. This table must have ex‐
       actly one row.

   Summary:
       Status:
         nb_cfg                      integer
         nb_cfg_timestamp            integer
       Common Columns:
         external_ids                map of string-string pairs
         options                     map of string-string pairs
       Common options:
         options                     map of string-string pairs
         options : enable_chassis_nb_cfg_update
                                     optional string
         Options for configuring BFD:
            options : bfd-min-rx     optional string
            options : bfd-decay-min-rx
                                     optional string
            options : bfd-min-tx     optional string
            options : bfd-mult       optional string
         Options for debug drop sampling:
            options : debug_drop_domain_id
                                     optional string
            options : debug_drop_collector_set
                                     optional string
         Options for configuring ovn-sbctl:
            options : sbctl_probe_interval
                                     optional string
       Connection Options:
         connections                 set of Connections
         ssl                         optional SSL
       Security Configurations:
         ipsec                       boolean

   Details:
     Status:

       This column allows a client to track the overall configuration state of
       the system.

       nb_cfg: integer
              Sequence number for the configuration. When a CMS  or  ovn-nbctl
              updates the northbound database, it increments the nb_cfg column
              in the NB_Global table in the northbound database. In turn, when
              ovn-northd  updates  the  southbound  database to bring it up to
              date with these changes, it updates  this  column  to  the  same
              value.

       nb_cfg_timestamp: integer
              The time at which ovn-northd last wrote nb_cfg to the southbound
              database,  in  milliseconds since the Unix epoch. Set atomically
              with each update to nb_cfg. Hypervisors read this value to  mea‐
              sure  end-to-end  propagation  latency from northbound commit to
              local datapath programming completion.

     Common Columns:

       external_ids: map of string-string pairs
              See External IDs at the beginning of this document.

       options: map of string-string pairs

     Common options:

       options: map of string-string pairs
              This column provides general key/value settings.  The  supported
              options are described individually below.

       options : enable_chassis_nb_cfg_update: optional string
              If set to false, ovn-controller will no longer update the nb_cfg
              column  in the Chassis_Private table of the OVN_Southbound data‐
              base. It will still update the  external_ids:ovn-nb-cfg  in  the
              local OVS integration bridge.

     Options for configuring BFD:

       These  options  apply when ovn-controller configures BFD on tunnels in‐
       terfaces.

       options : bfd-min-rx: optional string
              BFD option min-rx value to use when configuring  BFD  on  tunnel
              interfaces.

       options : bfd-decay-min-rx: optional string
              BFD  option  decay-min-rx  value  to use when configuring BFD on
              tunnel interfaces.

       options : bfd-min-tx: optional string
              BFD option min-tx value to use when configuring  BFD  on  tunnel
              interfaces.

       options : bfd-mult: optional string
              BFD  option mult value to use when configuring BFD on tunnel in‐
              terfaces.

     Options for debug drop sampling:

       options : debug_drop_domain_id: optional string
              If set to a 8-bit number and if debug_drop_collector_set is also
              configured, ovn-controller will add a  sample  action  to  every
              flow  that  does  not  come  from a logical flow that contains a
              ’drop’ action. The 8  most  significant  bits  of  the  observa‐
              tion_domain_id  field  will  be  those  specified  in  the   de‐‐
              bug_drop_domain_id. The 24 least significant bits of the  obser‐
              vation_domain_id field will be zero.

              The  observation_point_id will be set to the OpenFlow table num‐
              ber.

       options : debug_drop_collector_set: optional string
              If set to a 32-bit number ovn-controller will add a  sample  ac‐
              tion  to  every flow that does not come from a logical flow that
              contains a ’drop’ action. The sample action will have the speci‐
              fied collector_set_id. The value must match that  of  the  local
              OVS configuration as described in ovs-actions(7).

     Options for configuring ovn-sbctl:

       These options apply when ovn-sbctl connects to OVN Southbound database.

       options : sbctl_probe_interval: optional string
              The  inactivity  probe  interval  of  the  connection to the OVN
              Southbound database from ovn-sbctl utility, in milliseconds.  If
              the value is zero, it disables the connection keepalive feature.

              If the value is nonzero, then it will be forced to a value of at
              least 1000 ms.

              If  the  value  is  less  than zero, then the default inactivity
              probe interval for ovn-sbctl would be left intact (120000 ms).

     Connection Options:

       connections: set of Connections
              Database clients to  which  the  Open  vSwitch  database  server
              should  connect or on which it should listen, along with options
              for how these connections should be configured. See the  Connec‐‐
              tion table for more information.

       ssl: optional SSL
              Global SSL/TLS configuration.

     Security Configurations:

       ipsec: boolean
              Tunnel  encryption  configuration.  If  this column is set to be
              true, all OVN tunnels will be encrypted with IPsec.

Chassis TABLE
       Each row in this table represents a hypervisor or gateway  (a  chassis)
       in  the  physical  network.  Each  chassis, via ovn-controller/ovn-con‐‐
       troller-vtep, adds and updates its own row, and keeps a copy of the re‐
       maining rows to determine how to reach other hypervisors.

       When a chassis shuts down gracefully, it should  remove  its  own  row.
       (This  is  not  critical  because  resources  hosted on the chassis are
       equally unreachable regardless of whether the row  is  present.)  If  a
       chassis  shuts  down permanently without removing its row, some kind of
       manual or automatic cleanup is  eventually  needed;  we  can  devise  a
       process for that as necessary.

   Summary:
       name                          string (must be unique within table)
       hostname                      string
       nb_cfg                        integer
       other_config : ovn-bridge-mappings
                                     optional string
       other_config : datapath-type  optional string
       other_config : iface-types    optional string
       other_config : ovn-cms-options
                                     optional string
       other_config : is-interconn   optional string
       other_config : is-remote      optional string
       transport_zones               set of strings
       other_config : ovn-chassis-mac-mappings
                                     optional string
       Common Columns:
         external_ids                map of string-string pairs
       Encapsulation Configuration:
         encaps                      set of 1 or more Encaps
       Gateway Configuration:
         vtep_logical_switches       set of strings

   Details:
       name: string (must be unique within table)
              OVN  does  not  prescribe a particular format for chassis names.
              ovn-controller populates this column using  external_ids:system-
              id  in  the Open_vSwitch database’s Open_vSwitch table. ovn-con‐
              troller-vtep populates  this  column  with  name  in  the  hard‐
              ware_vtep database’s Physical_Switch table.

       hostname: string
              The  hostname of the chassis, if applicable. ovn-controller will
              populate this column with the hostname of the host it is running
              on. ovn-controller-vtep will leave this column empty.

       nb_cfg: integer
              Deprecated. This column is replaced by the nb_cfg column of  the
              Chassis_Private table.

       other_config : ovn-bridge-mappings: optional string
              ovn-controller  populates  this  key with the set of bridge map‐
              pings it has been configured to use. Other  applications  should
              treat  this key as read-only. See ovn-controller(8) for more in‐
              formation.

       other_config : datapath-type: optional string
              ovn-controller populates this key with the datapath type config‐
              ured in the datapath_type column of the Open_vSwitch  database’s
              Bridge  table. Other applications should treat this key as read-
              only. See ovn-controller(8) for more information.

       other_config : iface-types: optional string
              ovn-controller populates this key with the interface types  con‐
              figured in the iface_types column of the Open_vSwitch database’s
              Open_vSwitch  table. Other applications should treat this key as
              read-only. See ovn-controller(8) for more information.

       other_config : ovn-cms-options: optional string
              ovn-controller populates this key with the set of  options  con‐
              figured   in  the  external_ids:ovn-cms-options  column  of  the
              Open_vSwitch  database’s  Open_vSwitch   table.   See   ovn-con‐‐
              troller(8) for more information.

       other_config : is-interconn: optional string
              ovn-controller populates this key with the setting configured in
              the  external_ids:ovn-is-interconn  column  of  the Open_vSwitch
              database’s Open_vSwitch table. If set to true,  the  chassis  is
              used  as  an  interconnection gateway. See ovn-controller(8) for
              more information.

       other_config : is-remote: optional string
              ovn-ic set this key to true for remote  interconnection  gateway
              chassises  learned from the interconnection southbound database.
              See ovn-ic(8) for more information.

       transport_zones: set of strings
              ovn-controller populates this key with the transport zones  con‐
              figured  in  the  external_ids:ovn-transport-zones column of the
              Open_vSwitch  database’s  Open_vSwitch   table.   See   ovn-con‐‐
              troller(8) for more information.

       other_config : ovn-chassis-mac-mappings: optional string
              ovn-controller  populates  this key with the set of options con‐
              figured in the external_ids:ovn-chassis-mac-mappings  column  of
              the  Open_vSwitch  database’s  Open_vSwitch  table. See ovn-con‐‐
              troller(8) for more information.

     Common Columns:

       The overall purpose of these columns is described under Common  Columns
       at the beginning of this document.

       external_ids: map of string-string pairs

     Encapsulation Configuration:

       OVN  uses  encapsulation  to transmit logical dataplane packets between
       chassis.

       encaps: set of 1 or more Encaps
              Points to supported  encapsulation  configurations  to  transmit
              logical dataplane packets to this chassis. Each entry is a Encap
              record that describes the configuration.

     Gateway Configuration:

       A  gateway  is  a chassis that forwards traffic between the OVN-managed
       part of a logical network and a physical VLAN, extending a tunnel-based
       logical network into a physical network. Gateways are  typically  dedi‐
       cated  nodes  that  do  not host VMs and will be controlled by ovn-con‐‐
       troller-vtep.

       vtep_logical_switches: set of strings
              Stores all VTEP logical switch names connected by  this  gateway
              chassis.  The  Port_Binding table entry with options:vtep-physi‐‐
              cal-switch equal Chassis name,  and  options:vtep-logical-switch
              value  in Chassis vtep_logical_switches, will be associated with
              this Chassis.
Chassis_Private TABLE
       Each row in this table maintains per chassis private data that are  ac‐
       cessed  only  by the owning chassis (write only) and ovn-northd, not by
       any other chassis. These data are stored in this separate table instead
       of the Chassis table for performance considerations: the rows  in  this
       table  can be conditionally monitored by chassises so that each chassis
       only gets update notifications for its own row,  to  avoid  unnecessary
       chassis private data update flooding in a large scale deployment.

   Summary:
       name                          string (must be unique within table)
       chassis                       optional weak reference to Chassis
       nb_cfg                        integer
       nb_cfg_timestamp              integer
       Common Columns:
         external_ids                map of string-string pairs

   Details:
       name: string (must be unique within table)
              The name of the chassis that owns these chassis-private data.

       chassis: optional weak reference to Chassis
              The  reference  to Chassis table for the chassis that owns these
              chassis-private data.

       nb_cfg: integer
              Sequence number for the configuration. When  ovn-controller  up‐
              dates  the  configuration  of a chassis from the contents of the
              southbound database, it copies nb_cfg from the  SB_Global  table
              into this column.

       nb_cfg_timestamp: integer
              The timestamp when ovn-controller finishes processing the change
              corresponding to nb_cfg.

     Common Columns:

       The  overall purpose of these columns is described under Common Columns
       at the beginning of this document.

       external_ids: map of string-string pairs
Encap TABLE
       The encaps column in the Chassis table refers to rows in this table  to
       identify  how  OVN may transmit logical dataplane packets to this chas‐
       sis. Each chassis,  via  ovn-controller(8)  or  ovn-controller-vtep(8),
       adds and updates its own rows and keeps a copy of the remaining rows to
       determine how to reach other chassis.

   Summary:
       type                          string, either geneve or vxlan
       options                       map of string-string pairs
       options : csum                optional string, either true or false
       options : dst_port            optional string, containing an integer
       options : is_default          optional string, either true or false
       ip                            string
       chassis_name                  string

   Details:
       type: string, either geneve or vxlan
              The  encapsulation  to  use to transmit packets to this chassis.
              Hypervisors and gateways must use geneve or vxlan.

       options: map of string-string pairs
              Options for configuring the encapsulation,  which  may  be  type
              specific.

       options : csum: optional string, either true or false
              csum  indicates  whether  this  chassis can transmit and receive
              packets that include checksums with reasonable  performance.  It
              hints  to  senders  transmitting  data to this chassis that they
              should use checksums to  protect  OVN  metadata.  ovn-controller
              populates  this  key with the value defined in external_ids:ovn-
              encap-csum column of the  Open_vSwitch  database’s  Open_vSwitch
              table.  Other  applications  should treat this key as read-only.
              See ovn-controller(8) for more information.

              In terms of performance, checksumming actually significantly in‐
              creases throughput in most common cases when  running  on  Linux
              based  hosts  without NICs supporting encapsulation hardware of‐
              fload (around 60% for bulk traffic). The reason is  that  gener‐
              ally all NICs are capable of offloading transmitted and received
              TCP/UDP  checksums  (viewed  as ordinary data packets and not as
              tunnels). The benefit comes on the receive side where the  vali‐
              dated outer checksum can be used to additionally validate an in‐
              ner  checksum (such as TCP), which in turn allows aggregation of
              packets to be more efficiently handled by the rest of the stack.

              Not all devices see such a benefit. The most  notable  exception
              is  hardware VTEPs. These devices are designed to not buffer en‐
              tire packets in their switching engines and are therefore unable
              to efficiently compute or validate full packet checksums. In ad‐
              dition certain versions of the Linux  kernel  are  not  able  to
              fully  take advantage of encapsulation NIC offloads in the pres‐
              ence of checksums. (This is actually a pretty narrow corner case
              though: earlier versions of Linux  don’t  support  encapsulation
              offloads  at  all  and  later versions support both offloads and
              checksums well.)

              csum defaults to false for hardware VTEPs and true for all other
              cases.

              This option applies to geneve and vxlan encapsulations.

       options : dst_port: optional string, containing an integer
              If set, overrides the UDP destination port.

       options : is_default: optional string, either true or false
              When there are multiple encaps for a chassis with different IPs,
              this option indicates if the  encap  is  the  default  one  that
              matches  the  IP  in external_ids:ovn-encap-ip-default column of
              the Open_vSwitch database’s Open_vSwitch table.

       ip: string
              The IPv4 or IPv6 address of the encapsulation tunnel endpoint.

       chassis_name: string
              The name of the chassis that created this encap.

Address_Set TABLE
       This table contains address sets synced from the Address_Set  table  in
       the  OVN_Northbound  database  and  address  sets  generated  from  the
       Port_Group table in the OVN_Northbound database.

       See the documentation for the Address_Set table and Port_Group table in
       the OVN_Northbound database for details.

   Summary:
       name                          string (must be unique within table)
       addresses                     set of strings
       options                       map of string-string pairs

   Details:
       name: string (must be unique within table)

       addresses: set of strings

       options: map of string-string pairs
Port_Group TABLE
       This  table  contains  names  for  the  logical  switch  ports  in  the
       OVN_Northbound  database that belongs to the same group that is defined
       in Port_Group in the OVN_Northbound database.

   Summary:
       name                          string (must be unique within table)
       ports                         set of strings

   Details:
       name: string (must be unique within table)

       ports: set of strings
Logical_Flow TABLE
       Each row in this table represents one logical  flow.  ovn-northd  popu‐
       lates  this  table  with  logical  flows  that  implement the L2 and L3
       topologies specified in the OVN_Northbound database.  Each  hypervisor,
       via  ovn-controller,  translates  the logical flows into OpenFlow flows
       specific to its hypervisor and installs them into Open vSwitch.

       Logical flows are expressed in an OVN-specific format, described  here.
       A  logical datapath flow is much like an OpenFlow flow, except that the
       flows are written in terms of logical ports and logical  datapaths  in‐
       stead  of  physical  ports  and physical datapaths. Translation between
       logical and physical flows helps to ensure  isolation  between  logical
       datapaths.  (The  logical flow abstraction also allows the OVN central‐
       ized components to do less work, since they do not have  to  separately
       compute and push out physical flows to each chassis.)

       The default action when no flow matches is to drop packets.

       Architectural Logical Life Cycle of a Packet

       This  following  description  focuses  on  the  life  cycle of a packet
       through a logical datapath, ignoring physical details of the  implemen‐
       tation.  Please  refer to Architectural Physical Life Cycle of a Packet
       in ovn-architecture(7) for the physical information.

       The description here is written as if OVN itself executes these  steps,
       but  in  fact  OVN (that is, ovn-controller) programs Open vSwitch, via
       OpenFlow and OVSDB, to execute them on its behalf.

       At a high level, OVN passes each packet through the logical  datapath’s
       logical  ingress  pipeline,  which may output the packet to one or more
       logical port or logical multicast groups. For each such logical  output
       port,  OVN  passes  the  packet  through  the datapath’s logical egress
       pipeline, which may either drop the packet or deliver it to the  desti‐
       nation.  Between the two pipelines, outputs to logical multicast groups
       are expanded into logical ports,  so  that  the  egress  pipeline  only
       processes  a  single  logical  output  port  at a time. Between the two
       pipelines is also where, when necessary, OVN encapsulates a packet in a
       tunnel (or tunnels) to transmit to remote hypervisors.

       In more detail, to start, OVN searches the Logical_Flow table for a row
       with correct logical_datapath or  a  logical_dp_group,  a  pipeline  of
       ingress,  a  table_id of 0, and a match that is true for the packet. If
       none is found, OVN drops the packet. If OVN finds  more  than  one,  it
       chooses  the match with the highest priority. Then OVN executes each of
       the actions specified in the row’s actions column, in the order  speci‐
       fied.  Some actions, such as those to modify packet headers, require no
       further details. The next and output actions are special.

       The next action causes the above process to  be  repeated  recursively,
       except that OVN searches for table_id of 1 instead of 0. Similarly, any
       next  action  in a row found in that table would cause a further search
       for a table_id of 2, and so on. When  recursive  processing  completes,
       flow control returns to the action following next.

       The  output action also introduces recursion. Its effect depends on the
       current value of the outport field. Suppose outport designates a  logi‐
       cal  port. First, OVN compares inport to outport; if they are equal, it
       treats the output as a no-op by default. In the common case, where they
       are different, the packet enters the egress pipeline.  This  transition
       to  the  egress pipeline discards register data, e.g. reg0 ... reg9 and
       connection tracking state, to achieve uniform  behavior  regardless  of
       whether  the egress pipeline is on a different hypervisor (because reg‐
       isters aren’t preserved across tunnel encapsulation).

       To execute the egress pipeline, OVN again searches the Logical_Flow ta‐
       ble for a row with correct logical_datapath or  a  logical_dp_group,  a
       table_id of 0, a match that is true for the packet, but now looking for
       a pipeline of egress. If no matching row is found, the output becomes a
       no-op. Otherwise, OVN executes the actions for the matching flow (which
       is chosen from multiple, if necessary, as already described).

       In  the egress pipeline, the next action acts as already described, ex‐
       cept that it, of course, searches for egress flows. The output  action,
       however,  now  directly outputs the packet to the output port (which is
       now fixed, because outport is read-only within the egress pipeline).

       The description earlier assumed that  outport  referred  to  a  logical
       port.  If it instead designates a logical multicast group, then the de‐
       scription above still applies, with the addition of  fan-out  from  the
       logical  multicast  group  to  each logical port in the group. For each
       member of the group, OVN executes the logical  pipeline  as  described,
       with the logical output port replaced by the group member.

       Pipeline Stages

       ovn-northd  populates the Logical_Flow table with the logical flows de‐
       scribed in detail in ovn-northd(8).

   Summary:
       logical_datapath              optional Datapath_Binding
       logical_dp_group              optional Logical_DP_Group
       pipeline                      string, either egress or ingress
       table_id                      integer, in range 0 to 34
       priority                      integer, in range 0 to 65,535
       match                         string
       actions                       string
       tags                          map of string-string pairs
       controller_meter              optional string
       flow_desc                     optional string
       external_ids : stage-name     optional string
       external_ids : stage-hint     optional string, containing an uuid
       external_ids : source         optional string
       Common Columns:
         external_ids                map of string-string pairs

   Details:
       logical_datapath: optional Datapath_Binding
              The logical datapath to which the logical flow belongs.

       logical_dp_group: optional Logical_DP_Group
              The group of logical datapaths to which  the  logical  flow  be‐
              longs.  This  means  that  the  same logical flow belongs to all
              datapaths in a group.

       pipeline: string, either egress or ingress
              The primary flows used for deciding on  a  packet’s  destination
              are the ingress flows. The egress flows implement ACLs. See Log‐‐
              ical Life Cycle of a Packet, above, for details.

       table_id: integer, in range 0 to 34
              The  stage in the logical pipeline, analogous to an OpenFlow ta‐
              ble number.

       priority: integer, in range 0 to 65,535
              The flow’s priority. Flows with numerically higher priority take
              precedence over those with lower. If two logical datapath  flows
              with the same priority both match, then the one actually applied
              to the packet is undefined.

       match: string
              A  matching  expression.  OVN  provides  a  superset of OpenFlow
              matching capabilities, using a syntax similar to Boolean expres‐
              sions in a programming language.

              The most important components of match  expression  are  compar
              isons   between   symbols   and   constants,   e.g.  ip4.dst  ==
              192.168.0.1, ip.proto == 6, arp.op == 1, eth.type == 0x800.  The
              logical  AND  operator &&&& and logical OR operator || can combine
              comparisons into a larger expression.

              Matching expressions also support parentheses for grouping,  the
              logical  NOT  prefix operator !, and literals 0 and 1 to express
              ``false’’ or ``true,’’ respectively. The latter is useful by it‐
              self as a catch-all expression that matches every packet.

              Match expressions also support a kind of  function  syntax.  The
              following functions are supported:

              is_chassis_resident(lport)
                     Evaluates  to  true  on  a  chassis on which logical port
                     lport (a quoted string) resides, and to false  elsewhere.
                     This function was introduced in OVN 2.7.

              Symbols

              Type.  Symbols have integer or string type. Integer symbols have
              a width in bits.

              Kinds. There are three kinds of symbols:

              •      Fields. A field symbol  represents  a  packet  header  or
                     metadata field. For example, a field named vlan.tci might
                     represent the VLAN TCI field in a packet.

                     A  field  symbol can have integer or string type. Integer
                     fields can be nominal or ordinal (see Level  of  Measure‐‐
                     ment, below).

              •      Subfields.  A subfield represents a subset of bits from a
                     larger field. For example, a field vlan.vid might be  de‐
                     fined as an alias for vlan.tci[0..11]. Subfields are pro‐
                     vided  for  syntactic  convenience,  because it is always
                     possible to instead refer to a  subset  of  bits  from  a
                     field directly.

                     Only ordinal fields (see Level of Measurement, below) may
                     have subfields. Subfields are always ordinal.

              •      Predicates.  A  predicate  is shorthand for a Boolean ex‐
                     pression. Predicates may be used much like 1-bit  fields.
                     For example, ip4 might expand to eth.type == 0x800. Pred‐
                     icates are provided for syntactic convenience, because it
                     is  always possible to instead specify the underlying ex‐
                     pression directly.

                     A predicate whose expansion refers to any  nominal  field
                     or  predicate  (see Level of Measurement, below) is nomi‐
                     nal; other predicates have Boolean level of measurement.

              Level              of              Measurement.              See
              http://en.wikipedia.org/wiki/Level_of_measurement  for  the sta‐
              tistical concept on which this classification  is  based.  There
              are three levels:

              •      Ordinal.  In statistics, ordinal values can be ordered on
                     a scale. OVN considers a field (or subfield) to be  ordi‐
                     nal  if  its  bits  can be examined individually. This is
                     true for  the  OpenFlow  fields  that  OpenFlow  or  Open
                     vSwitch makes ``maskable.’’

                     Any use of an ordinal field may specify a single bit or a
                     range  of  bits,  e.g. vlan.tci[13..15] refers to the PCP
                     field within the VLAN TCI, and eth.dst[40] refers to  the
                     multicast bit in the Ethernet destination address.

                     OVN  supports all the usual arithmetic relations (==, !=,
                     =, >gt;>gt;, and >gt;>gt;=) on ordinal fields and their  subfields,
                     because  OVN  can  implement  these  in OpenFlow and Open
                     vSwitch as collections of bitwise tests.

              •      Nominal. In statistics, nominal values cannot be usefully
                     compared except for equality. OpenFlow port numbers, Eth‐
                     ernet types, and IP protocols are examples: all of  these
                     are  just identifiers assigned arbitrarily with no deeper
                     meaning. In OpenFlow and  Open  vSwitch,  bits  in  these
                     fields generally aren’t individually addressable.

                     OVN  only supports arithmetic tests for equality on nomi‐
                     nal fields, because OpenFlow and Open vSwitch provide  no
                     way for a flow to efficiently implement other comparisons
                     on  them. (A test for inequality can be sort of built out
                     of two flows with different priorities, but OVN  matching
                     expressions  always  generate  flows with a single prior‐
                     ity.)

                     String fields are always nominal.

              •      Boolean. A nominal field that has only two values, 0  and
                     1,  is  somewhat exceptional, since it is easy to support
                     both equality and inequality tests on such a  field:  ei‐
                     ther one can be implemented as a test for 0 or 1.

                     Only  predicates (see above) have a Boolean level of mea‐
                     surement.

                     This isn’t a standard level of measurement.

              Prerequisites. Any symbol can have prerequisites, which are  ad‐
              ditional  condition  implied by the use of the symbol. For exam‐
              ple, icmp4.type symbol  might  have  prerequisite  icmp4,  which
              would  cause  an expression icmp4.type == 0 to be interpreted as
              icmp4.type ==  0  &&&&  icmp4,  which  would  in  turn  expand  to
              icmp4.type == 0 &&&& eth.type == 0x800 &&&& ip4.proto == 1 (assuming
              icmp4 is a predicate defined as suggested under Types above).

              Relational operators

              All  of  the standard relational operators ==, !=, =, >gt;>gt;, and
              >gt;>gt;= are supported. Nominal fields support only  ==  and  !=,  and
              only  in  a  positive sense when outer ! are taken into account,
              e.g. given string field inport, inport == "eth0" and !(inport !=
              "eth0") are acceptable, but not inport != "eth0".

              The implementation of == (or != when it is negated), is more ef‐
              ficient than that of the other relational operators.

              Constants

              Integer constants may be expressed in decimal, hexadecimal  pre‐
              fixed by 0x, or as dotted-quad IPv4 addresses, IPv6 addresses in
              their  standard  forms, or Ethernet addresses as colon-separated
              hex digits. A constant in any of these forms may be followed  by
              a  slash  and  a second constant (the mask) in the same form, to
              form a masked constant. IPv4 and IPv6 masks may be given as  in‐
              tegers, to express CIDR prefixes.

              String  constants have the same syntax as quoted strings in JSON
              (thus, they are Unicode strings).

              Some operators support sets of constants  written  inside  curly
              braces  { ... }. Commas between elements of a set, and after the
              last elements, are optional. With ==, ``field  ==  {  constant1,
              constant2,  ...  }’’ is syntactic sugar for ``field == constant1
              || field == constant2 || .... Similarly, ``field != { constant1,
              constant2, ... }’’ is equivalent  to  ``field  !=  constant1  &&&&
              field != constant2 &&&& ...’’.

              You may refer to a set of IPv4, IPv6, or MAC addresses stored in
              the Address_Set table by its name. An Address_Set with a name of
              set1 can be referred to as $set1.

              You  may  refer to a group of logical switch ports stored in the
              Port_Group table by its name.  An  Port_Group  with  a  name  of
              port_group1 can be referred to as @port_group1.

              Additionally, you may refer to the set of addresses belonging to
              a  group  of logical switch ports stored in the Port_Group table
              by its name followed by a suffix ’_ip4’/’_ip6’. The IPv4 address
              set of a Port_Group with a name of port_group1 can  be  referred
              to  as  $port_group1_ip4,  and  the IPv6 address set of the same
              Port_Group can be referred to as $port_group1_ip6

              Miscellaneous

              Comparisons may name the symbol  or  the  constant  first,  e.g.
              tcp.src == 80 and 80 == tcp.src are both acceptable.

              Tests  for  a range may be expressed using a syntax like 1024 =
              tcp.src = 49151, which is equivalent  to  1024  =  tcp.src  &&&&
              tcp.src = 49151.

              For  a  one-bit  field  or  predicate,  a mention of its name is
              equivalent to symbol == 1, e.g. vlan.present  is  equivalent  to
              vlan.present  == 1. The same is true for one-bit subfields, e.g.
              vlan.tci[12]. There is no technical limitation  to  implementing
              the  same  for ordinal fields of all widths, but the implementa‐
              tion is expensive enough that the syntax parser requires writing
              an explicit  comparison  against  zero  to  make  mistakes  less
              likely,  e.g.  in  tcp.src  != 0 the comparison against 0 is re‐
              quired.

              Operator precedence is as shown below, from highest  to  lowest.
              There  are  two  exceptions  where parentheses are required even
              though the table would suggest that they are not: &&&& and ||  re‐
              quire parentheses when used together, and ! requires parentheses
              when  applied  to a relational expression. Thus, in (eth.type ==
              0x800 || eth.type == 0x86dd) &&&& ip.proto == 6 or !(arp.op == 1),
              the parentheses are mandatory.

              •      ()==   !=   =   >gt;>gt;   >gt;>gt;=!

              •      &&&&   ||

              Comments may be introduced by //, which extends to the next new-
              line. Comments within a line may be bracketed by /* and */. Mul‐
              tiline comments are not supported.

              Symbols

              Most of the symbols below have integer  type.  Only  inport  and
              outport have string type. inport names a logical port. Thus, its
              value  is  a logical_port name from the Port_Binding table. out‐‐
              port may name a logical port, as inport, or a logical  multicast
              group  defined  in  the Multicast_Group table. For both symbols,
              only names within the flow’s logical datapath may be used.

              The regX symbols are 32-bit integers.  The  xxregX  symbols  are
              128-bit  integers,  which  overlay four of the 32-bit registers:
              xxreg0 overlays reg0 through reg3, with reg0 supplying the most-
              significant bits  of  xxreg0  and  reg3  the  least-significant.
              xxreg1 similarly overlays reg4 through reg7.

              •      reg0...reg9xxreg0 xxreg1inport outportflags.loopbackpkt.marketh.src eth.dst eth.typevlan.tci vlan.vid vlan.pcp vlan.presentip.proto ip.dscp ip.ecn ip.ttl ip.fragip4.src ip4.dstip6.src ip6.dst ip6.labelarp.op arp.spa arp.tpa arp.sha arp.thararp.op rarp.spa rarp.tpa rarp.sha rarp.thatcp.src tcp.dst tcp.flagsudp.src udp.dstsctp.src sctp.dsticmp4.type icmp4.codeicmp6.type icmp6.codend.target nd.sll nd.tllct_mark ct_labelct_state,   which  has  several  Boolean  subfields.  The
                     ct_next action initializes the following subfields:

                     •      ct.trk: Always set to true by ct_next to  indicate
                            that  connection  tracking  has  taken  place. All
                            other ct subfields have ct.trk as a prerequisite.

                     •      ct.new: True for a new flow

                     •      ct.est: True for an established flow

                     •      ct.rel: True for a related flow

                     •      ct.rpl: True for a reply flow

                     •      ct.inv: True for a connection entry in a bad state

                     The ct_dnat, ct_snat, and ct_lb_mark  actions  initialize
                     the following subfields:

                     •      ct.dnat:  True  for  a packet whose destination IP
                            address has been changed.

                     •      ct.snat: True for a packet whose source IP address
                            has been changed.

              The following predicates are supported:

              •      eth.bcast expands to eth.dst == ff:ff:ff:ff:ff:ffeth.mcast expands to eth.dst[40]eth.mcastv6 expands to eth.dst[32..47] == 0x3333vlan.present expands to vlan.tci[12]ip4 expands to eth.type == 0x800ip4.src_mcast expands to ip4.src[28..31] == 0xeip4.mcast expands to ip4.dst[28..31] == 0xeip6 expands to eth.type == 0x86ddip expands to ip4 || ip6icmp4 expands to ip4 &&&& ip.proto == 1icmp6 expands to ip6 &&&& ip.proto == 58icmp expands to icmp4 || icmp6ip.is_frag expands to ip.frag[0]ip.later_frag expands to ip.frag[1]ip.first_frag expands to ip.is_frag &&&& !ip.later_fragarp expands to eth.type == 0x806rarp expands to eth.type == 0x8035ip6.mcast expands to eth.mcastv6 &&&& ip6.dst[120..127]  ==
                     0xffnd expands to icmp6.type == {135, 136} &&&& icmp6.code == 0
                     &&&& ip.ttl == 255nd_ns  expands to icmp6.type == 135 &&&& icmp6.code == 0 &&&&
                     ip.ttl == 255nd_ns_mcast expands to ip6.mcast  &&&& icmp6.type == 135 &&&&
                     icmp6.code == 0 &&&& ip.ttl == 255nd_na expands to icmp6.type == 136 &&&& icmp6.code == 0  &&&&
                     ip.ttl == 255nd_rs  expands to icmp6.type == 133 &&&& icmp6.code == 0 &&&&
                     ip.ttl == 255nd_ra expands to icmp6.type == 134 &&&& icmp6.code == 0  &&&&
                     ip.ttl == 255tcp expands to ip.proto == 6udp expands to ip.proto == 17sctp expands to ip.proto == 132

       actions: string
              Logical  datapath  actions, to be executed when the logical flow
              represented by this row is the highest-priority match.

              Actions share lexical syntax with the match column. An empty set
              of actions (or one that contains just white space or  comments),
              or  a  set  of  actions  that consists of just drop;, causes the
              matched packets to be dropped. Otherwise, the column should con‐
              tain a sequence of actions, each terminated by a semicolon.

              The following actions are defined:

              output;
                     In the ingress pipeline, this action executes the  egress
                     pipeline  as  a  subroutine.  If  outport names a logical
                     port, the egress pipeline executes once; if it is a  mul‐
                     ticast group, the egress pipeline runs once for each log‐
                     ical port in the group.

                     In  the  egress pipeline, this action performs the actual
                     output to  the  outport  logical  port.  (In  the  egress
                     pipeline, outport never names a multicast group.)

                     By  default,  output  to  the  input  port  is implicitly
                     dropped, that is, output becomes a no-op  if  outport  ==
                     inport.  Occasionally  it  may be useful to override this
                     behavior, e.g. to send an ARP reply to an ARP request; to
                     do so, use flags.loopback = 1  to  allow  the  packet  to
                     "hair-pin" back to the input port.

              next;
              next(table);
              next(pipeline=pipeline, table=table);
                   Executes  the given logical datapath table in pipeline as a
                   subroutine. The default table is  just  after  the  current
                   one. If pipeline is specified, it may be ingress or egress;
                   the  default  pipeline  is the one currently executing. Ac‐
                   tions in the both ingress and egress pipeline can use  next
                   to  jump  across the other pipeline. Actions in the ingress
                   pipeline should use next to jump into the specific table of
                   egress pipeline only if it is certain that the packets  are
                   local and not tunnelled and wants to skip certain stages in
                   the packet processing.

              field = constant;
                   Sets  data  or  metadata field field to constant value con
                   stant, e.g. outport = "vif0"; to  set  the  logical  output
                   port.  To  set  only a subset of bits in a field, specify a
                   subfield for field or a masked constant, e.g. one  may  use
                   vlan.pcp[2] = 1; or vlan.pcp = 4/4; to set the most signif‐
                   icant bit of the VLAN PCP.

                   Assigning  to  a  field  with prerequisites implicitly adds
                   those prerequisites to match; thus,  for  example,  a  flow
                   that  sets tcp.dst applies only to TCP flows, regardless of
                   whether its match mentions any TCP field.

                   Not all fields are modifiable (e.g. eth.type  and  ip.proto
                   are  read-only),  and not all modifiable fields may be par‐
                   tially modified (e.g. ip.ttl must be assigned as a  whole).
                   The outport field is modifiable in the ingress pipeline but
                   not in the egress pipeline.

              ovn_field = constant;
                   Sets OVN field ovn_field to constant value constant.

                   OVN supports setting the values of certain fields which are
                   not yet supported in OpenFlow to set or modify them.

                   Below are the supported OVN fields:

                   •      icmp4.frag_mtu icmp6.frag_mtu

                          This  field  sets  the  low-order  16  bits  of  the
                          ICMP{4,6} header field that is labelled "unused"  in
                          the  ICMP  specification  as defined in the RFC 1191
                          with the value specified in constant.

                   •      icmp4.inner_ip4.src

                          This field rewrites the source IPv4 address  carried
                          in  the  inner (original-packet) IPv4 header that is
                          embedded in the payload of an ICMPv4 error  message,
                          setting it to constant. The inner IPv4 header check‐
                          sum  and  the outer ICMP checksum are recomputed ac‐
                          cordingly. The action has no effect on packets  that
                          are not ICMPv4 errors.

                          It  can  be  used by stateless NAT to fix up inbound
                          ICMPv4 errors, for example Fragmentation Needed mes‐
                          sages used for Path  MTU  discovery  (RFC  1191).  A
                          stateless dnat_and_snat rule rewrites only the outer
                          destination of such an error, while the embedded in‐
                          ner  header still carries the external (post-NAT) IP
                          as its source. As a result conntrack  in  the  down‐
                          stream  logical  switch  cannot  correlate the error
                          with the tracked flow. Un-NATing  the  inner  source
                          back to the logical IP lets conntrack relate the er‐
                          ror and lets the originating workload honor the PMTU
                          signal.

                          Eg. icmp4.inner_ip4.src = 10.0.0.10;

              field1 = field2;
                   Sets  data or metadata field field1 to the value of data or
                   metadata field field2, e.g. reg0 = ip4.src; copies  ip4.src
                   into reg0. To modify only a subset of a field’s bits, spec‐
                   ify  a subfield for field1 or field2 or both, e.g. vlan.pcp
                   = reg0[0..2]; copies the  least-significant  bits  of  reg0
                   into the VLAN PCP.

                   field1 and field2 must be the same type, either both string
                   or  both  integer  fields. If they are both integer fields,
                   they must have the same width.

                   If field1 or field2 has prerequisites, they are  added  im‐
                   plicitly  to  match.  It is possible to write an assignment
                   with  contradictory  prerequisites,  such  as   ip4.src   =
                   ip6.src[0..31];, but the contradiction means that a logical
                   flow with such an assignment will never be matched.

              field1 ->gt;>gt; field2;
                   Similar  to field1 = field2; except that the two values are
                   exchanged instead of copied. Both field1  and  field2  must
                   modifiable.

              push(field);
                   Push the value of field to the stack top.

              pop(field);
                   Pop  the stack top and store the value to field, which must
                   be modifiable.

              ip.ttl--;
                   Decrements the IPv4 or IPv6 TTL. If this would make the TTL
                   zero or negative, then processing of the packet  halts;  no
                   further  actions  are  processed.  (To properly handle such
                   cases, a higher-priority flow should match on ip.ttl == {0,
                   1};.)

                   Prerequisite: ip

              ct_next;
              ct_next(dnat);
              ct_next(snat);
                   Apply  connection  tracking  to  the   flow,   initializing
                   ct_state  for matching in later tables. Automatically moves
                   on to the next table, as if followed by next.

                   As a side effect, IP  fragments  will  be  reassembled  for
                   matching. If a fragmented packet is output, then it will be
                   sent  with  any overlapping fragments squashed. The connec‐
                   tion tracking state is scoped by the logical port when  the
                   action  is used in a flow for a logical switch, so overlap‐
                   ping addresses may be used. To allow traffic related to the
                   matched flow, execute ct_commit . Connection tracking state
                   is scoped by the logical topology when the action  is  used
                   in a flow for a router.

                   It  is  possible  to  have actions follow ct_next, but they
                   will not have access to any of its side-effects and are not
                   generally useful.

              ct_commit { };
              ct_commit { ct_mark=value[/mask]; };
              ct_commit { ct_label=value[/mask]; };
              ct_commit { ct_mark=value[/mask]; ct_label=value[/mask]; };
                   Commit the flow to the connection tracking entry associated
                   with   it   by   a   previous   call   to   ct_next.   When
                   ct_mark=value[/mask]  and/or ct_label=value[/mask] are sup‐
                   plied, ct_mark and/or ct_label will be set  to  the  values
                   indicated by value[/mask] on the connection tracking entry.
                   ct_mark is a 32-bit field. ct_label is a 128-bit field. The
                   value[/mask] should be specified in hex string if more than
                   64bits are to be used. Registers and other named fields can
                   be  used  for  value.  ct_mark  and ct_label may be sub-ad‐
                   dressed in order to have specific bits set.

                   Note that if you want processing to continue  in  the  next
                   table,  you  must  execute the next action after ct_commit.
                   You may also leave out next which  will  commit  connection
                   tracking  state,  and  then  drop the packet. This could be
                   useful for setting ct_mark on a connection  tracking  entry
                   before dropping a packet, for example.

              ct_commit_to_zone(dnat);
              ct_commit_to_zone(snat);
                   Commit  the  flow  to  the  specific zone in the connection
                   tracker. The packet is then automatically sent to the  next
                   tables as if followed by next; action. The next tables will
                   see  the  changes  in  the  packet caused by the connection
                   tracker.

                   Note that this action is meaningful  only  in  the  Logical
                   Router Datapath as the Logical Switch Datapath does not use
                   separate  connection  tracking  zones. Using this action in
                   Logical Switch Datapath falls back to committing  the  flow
                   into the logical port’s conntrack zone.

              ct_dnat;
              ct_dnat(IP);
                   ct_dnat  sends  the packet through the DNAT zone in connec‐
                   tion tracking table to unDNAT any packet that was DNATed in
                   the opposite direction. The packet  is  then  automatically
                   sent to the next tables as if followed by next; action. The
                   next  tables  will  see the changes in the packet caused by
                   the connection tracker.

                   ct_dnat(IP) sends the  packet  through  the  DNAT  zone  to
                   change  the destination IP address of the packet to the one
                   provided inside the parentheses and commits the connection.
                   The packet is then automatically sent to the next tables as
                   if followed by next; action. The next tables will  see  the
                   changes in the packet caused by the connection tracker.

              ct_snat;
              ct_snat(IP);
                   ct_snat  sends  the  packet through the SNAT zone to unSNAT
                   any packet that was SNATed in the opposite  direction.  The
                   packet  is automatically sent to the next tables as if fol‐
                   lowed by the next; action. The next  tables  will  see  the
                   changes in the packet caused by the connection tracker.

                   ct_snat(IP)  sends  the  packet  through  the  SNAT zone to
                   change the source IP address of the packet to the one  pro‐
                   vided  inside  the  parentheses and commits the connection.
                   The packet is then automatically sent to the next tables as
                   if followed by next; action. The next tables will  see  the
                   changes in the packet caused by the connection tracker.

              ct_dnat_in_czone;
              ct_dnat_in_czone(IP);
                   ct_dnat_in_czone  sends  the  packet through the common NAT
                   zone (used for both DNAT and SNAT) in  connection  tracking
                   table  to unDNAT any packet that was DNATed in the opposite
                   direction. The packet is then  automatically  sent  to  the
                   next tables as if followed by next; action. The next tables
                   will see the changes in the packet caused by the connection
                   tracker.

                   ct_dnat_in_czone(IP)  sends  the  packet through the common
                   NAT zone to change the destination IP address of the packet
                   to the one provided inside the parentheses and commits  the
                   connection.  The  packet  is then automatically sent to the
                   next tables as if followed by next; action. The next tables
                   will see the changes in the packet caused by the connection
                   tracker.

              ct_snat_in_czone;
              ct_snat_in_czone(IP);
                   ct_snat_in_czone sends the packet through  the  common  NAT
                   zone  to  unSNAT any packet that was SNATed in the opposite
                   direction. The packet is automatically sent to the next ta‐
                   bles as if followed by the next; action.  The  next  tables
                   will see the changes in the packet caused by the connection
                   tracker.

                   ct_snat_in_czone(IP)  sends  the  packet through the common
                   NAT zone to change the source IP address of the  packet  to
                   the  one  provided  inside  the parentheses and commits the
                   connection. The packet is then automatically  sent  to  the
                   next tables as if followed by next; action. The next tables
                   will see the changes in the packet caused by the connection
                   tracker.

              ct_clear;
                   Clears connection tracking state.

              ct_commit_nat;
                   Applies NAT and commits the connection to the CT. Automati‐
                   cally  moves  on to the next table, as if followed by next.
                   This is very useful for connections  that  are  in  related
                   state  for  already existing connections and allows the NAT
                   to be applied to them as well.

              clone { action; ... };
                   Makes a copy of the packet  being  processed  and  executes
                   each  action  on  the copy. Actions following the clone ac‐
                   tion, if any, apply to  the  original,  unmodified  packet.
                   This  can  be  used  as  a  way to ``save and restore’’ the
                   packet around a set of  actions  that  may  modify  it  and
                   should not persist.

              arp { action; ... };
                   Temporarily  replaces the IPv4 packet being processed by an
                   ARP packet and executes  each  nested  action  on  the  ARP
                   packet.  Actions following the arp action, if any, apply to
                   the original, unmodified packet.

                   The ARP packet that this action operates on is  initialized
                   based on the IPv4 packet being processed, as follows. These
                   are  default  values  that the nested actions will probably
                   want to change:

                   •      eth.src unchanged

                   •      eth.dst unchanged

                   •      eth.type = 0x0806arp.op = 1 (ARP request)

                   •      arp.sha copied from eth.srcarp.spa copied from ip4.srcarp.tha = 00:00:00:00:00:00arp.tpa copied from ip4.dst

                   The ARP packet has the same VLAN header, if any, as the  IP
                   packet it replaces.

                   Prerequisite: ip4

              get_arp(P, A);
                   Parameters:  logical port string field P, 32-bit IP address
                   field A.

                   Looks up A in P’s mac binding table. If an entry is  found,
                   stores  its  Ethernet  address in eth.dst, otherwise stores
                   00:00:00:00:00:00 in eth.dst.

                   Example: get_arp(outport, ip4.dst);

              put_arp(P, A, E);
                   Parameters: logical port string field P, 32-bit IP  address
                   field A, 48-bit Ethernet address field E.

                   Adds  or updates the entry for IP address A in logical port
                   P’s mac binding table, setting its Ethernet address to E.

                   Example: put_arp(inport, arp.spa, arp.sha);

              R = lookup_arp(P, A, M);
                   Parameters: logical port string field P, 32-bit IP  address
                   field A, 48-bit MAC address field M.

                   Result: stored to a 1-bit subfield R.

                   Looks  up  A and M in P’s mac binding table. If an entry is
                   found, stores 1 in the 1-bit subfield R, else 0.

                   Example: reg0[0] = lookup_arp(inport, arp.spa, arp.sha);

              R = lookup_arp_ip(P, A);
                   Parameters: logical port string field P, 32-bit IP  address
                   field A.

                   Result: stored to a 1-bit subfield R.

                   Looks  up A in P’s mac binding table. If an entry is found,
                   stores 1 in the 1-bit subfield R, else 0.

                   Example: reg0[0] = lookup_arp_ip(inport, arp.spa);

              R = chk_evpn_arp(A);
                   Parameters: 32-bit or 128-bit IP address field A.

                   Result: stored to a 1-bit subfield R.

                   Looks up A in the EVPN ARP side table for the current logi‐
                   cal datapath. If a matching entry is found, stores 1 in the
                   1-bit subfield R and loads the resolved  MAC  address  into
                   eth.dst.  Otherwise,  stores 0 in R and eth.dst is left un‐
                   changed.

                   This action is used for EVPN ARP/ND suppression on  logical
                   switches. When an ARP request or ND solicitation targets an
                   IP address that was learned via EVPN, the switch can proxy-
                   reply  using  the  MAC from eth.dst instead of flooding the
                   request to remote VTEPs.

                   Example: reg9[5] = chk_evpn_arp(arp.tpa);

              P = get_fdb(A);
                   Parameters: 48-bit MAC address field A.

                   Looks up A in the FDB table. If an entry is  found,  stores
                   the logical port key to the out parameter P.

                   Example: outport = get_fdb(eth.src);

              P = get_remote_fdb(A);
                    Parameters: 48-bit MAC address field A.

                   Result: stored to a logical port field P.

                   Looks  up  A in the remote FDB table. If an entry is found,
                   store the logical port key to the out parameter P. This  is
                   similar  to get_fdb but looks up remote FDB entries learned
                   from other chassis.

                   Example: outport = get_remote_fdb(eth.dst);

              put_fdb(P, A);
                   Parameters: logical port string field P, 48-bit MAC address
                   field A.

                   Adds or updates the entry for Ethernet address A in the FDB
                   table, setting its logical port key to P.

                   Example: put_fdb(inport, eth.src);

              R = lookup_fdb(P, A);
                   Parameters: logical port string field P, 48-bit MAC address
                   field A.

                   Result: stored to a 1-bit subfield R.

                   Looks up A in the FDB table. If an entry is found  and  the
                   logical port key is P, P, stores 1 in the 1-bit subfield R,
                   else 0. If flags.localnet is set then 1 is stored if an en‐
                   try  is  found and the logical port key is P or if an entry
                   is found and the entry port type is VIF.

                   Example: reg0[0] = lookup_fdb(inport, eth.src);

              nf_learn_orig_inport(ipv6 = B);
                   Records the logical input port that the current  IP  packet
                   entered  the  logical  switch  on  by  learning a flow. The
                   learned flow matches a later packet of the same flow  (same
                   logical  datapath  and IP source and destination addresses)
                   when its logical output port equals that input  port,  that
                   is,  when  the  packet  is about to be sent back out of the
                   port it originally arrived on.

                   B must be true to learn an IPv6 flow or false to  learn  an
                   IPv4  flow.  The learned flow has a 60 second idle timeout.
                   This action is used together  with  nf_lookup_orig_inport()
                   to  drop  the duplicate copies that a network function (NF)
                   redirection can produce when the destination MAC address is
                   still unknown, which  would  otherwise  cause  MAC  address
                   flaps or L2 loops.

                   Example: nf_learn_orig_inport(ipv6 = false);

              R = nf_lookup_orig_inport();
                   Result: stored to a 1-bit subfield R.

                   Looks up the flow learned by nf_learn_orig_inport(). Stores
                   1  in  R if the current packet matches a learned flow, that
                   is, if it is an IP  packet  that,  after  network  function
                   redirection,  is  about  to be sent back out of the logical
                   input port it originally arrived on. Otherwise stores 0.

                   Example: reg0[0] = nf_lookup_orig_inport();

              nd_ns { action; ... };
                   Temporarily replaces the IPv6 packet being processed by  an
                   IPv6  Neighbor Solicitation packet and executes each nested
                   action on the IPv6 NS packet. Actions following  the  nd_ns
                   action, if any, apply to the original, unmodified packet.

                   The IPv6 NS packet that this action operates on is initial‐
                   ized  based on the IPv6 packet being processed, as follows.
                   These are default values that the nested actions will prob‐
                   ably want to change:

                   •      eth.src unchanged

                   •      eth.dst set to IPv6 multicast MAC address

                   •      eth.type = 0x86ddip6.src copied from ip6.srcip6.dst set to IPv6 Solicited-Node multicast address

                   •      icmp6.type = 135 (Neighbor Solicitation)

                   •      nd.target copied from ip6.dst

                   The IPv6 NS packet has the same VLAN header, if any, as the
                   IP packet it replaces.

                   Prerequisite: ip6

              nd_na { action; ... };
                   Temporarily replaces the IPv6 neighbor solicitation  packet
                   being  processed  by  an  IPv6  neighbor advertisement (NA)
                   packet and executes each nested action on  the  NA  packet.
                   Actions  following  the  nd_na action, if any, apply to the
                   original, unmodified packet.

                   The NA packet that this action operates on  is  initialized
                   based on the IPv6 packet being processed, as follows. These
                   are  default  values  that the nested actions will probably
                   want to change:

                   •      eth.dst exchanged with eth.srceth.type = 0x86ddip6.dst copied from ip6.srcip6.src copied from nd.targeticmp6.type = 136 (Neighbor Advertisement)

                   •      nd.target unchanged

                   •      nd.sll = 00:00:00:00:00:00nd.tll copied from eth.dst

                   The ND packet has the same VLAN header, if any, as the IPv6
                   packet it replaces.

                   Prerequisite: nd_ns

              nd_na_router { action; ... };
                   Temporarily replaces the IPv6 neighbor solicitation  packet
                   being  processed  by  an  IPv6  neighbor advertisement (NA)
                   packet, sets ND_NSO_ROUTER in the RSO  flags  and  executes
                   each  nested action on the NA packet. Actions following the
                   nd_na_router action, if any, apply to the original, unmodi‐
                   fied packet.

                   The NA packet that this action operates on  is  initialized
                   based on the IPv6 packet being processed, as follows. These
                   are  default  values  that the nested actions will probably
                   want to change:

                   •      eth.dst exchanged with eth.srceth.type = 0x86ddip6.dst copied from ip6.srcip6.src copied from nd.targeticmp6.type = 136 (Neighbor Advertisement)

                   •      nd.target unchanged

                   •      nd.sll = 00:00:00:00:00:00nd.tll copied from eth.dst

                   The ND packet has the same VLAN header, if any, as the IPv6
                   packet it replaces.

                   Prerequisite: nd_ns

              get_nd(P, A);
                   Parameters: logical port string field P, 128-bit  IPv6  ad‐
                   dress field A.

                   Looks  up A in P’s mac binding table. If an entry is found,
                   stores its Ethernet address in  eth.dst,  otherwise  stores
                   00:00:00:00:00:00 in eth.dst.

                   Example: get_nd(outport, ip6.dst);

              put_nd(P, A, E);
                   Parameters:  logical  port string field P, 128-bit IPv6 ad‐
                   dress field A, 48-bit Ethernet address field E.

                   Adds or updates the entry for IPv6  address  A  in  logical
                   port P’s mac binding table, setting its Ethernet address to
                   E.

                   Example: put_nd(inport, nd.target, nd.tll);

              R = lookup_nd(P, A, M);
                   Parameters: logical port string field P, 128-bit IP address
                   field A, 48-bit MAC address field M.

                   Result: stored to a 1-bit subfield R.

                   Looks  up  A and M in P’s mac binding table. If an entry is
                   found, stores 1 in the 1-bit subfield R, else 0.

                   Example: reg0[0] = lookup_nd(inport, ip6.src, eth.src);

              R = lookup_nd_ip(P, A);
                   Parameters: logical port string field P, 128-bit IP address
                   field A.

                   Result: stored to a 1-bit subfield R.

                   Looks up A in P’s mac binding table. If an entry is  found,
                   stores 1 in the 1-bit subfield R, else 0.

                   Example: reg0[0] = lookup_nd_ip(inport, ip6.src);

              R = put_dhcp_opts(D1 = V1, D2 = V2, ..., Dn = Vn);
                   Parameters: one or more DHCP option/value pairs, which must
                   include an offerip option (with code 0).

                   Result: stored to a 1-bit subfield R.

                   Valid only in the ingress pipeline.

                   When  this  action  is  applied  to  a  DHCP request packet
                   (DHCPDISCOVER or DHCPREQUEST), it changes the packet into a
                   DHCP reply (DHCPOFFER or DHCPACK,  respectively),  replaces
                   the  options by those specified as parameters, and stores 1
                   in R.

                   When this action is applied to a non-DHCP packet or a  DHCP
                   packet  that  is not DHCPDISCOVER or DHCPREQUEST, it leaves
                   the packet unchanged and stores 0 in R.

                   The contents of the DHCP_Options table control the DHCP op‐
                   tion names and values that this action supports.

                   Example: reg0[0] = put_dhcp_opts(offerip = 10.0.0.2, router
                   = 10.0.0.1, netmask = 255.255.255.0, dns_server = {8.8.8.8,
                   7.7.7.7});

              R = put_dhcpv6_opts(D1 = V1, D2 = V2, ..., Dn = Vn);
                   Parameters: one or more DHCPv6 option/value pairs.

                   Result: stored to a 1-bit subfield R.

                   Valid only in the ingress pipeline.

                   When this action is applied to a DHCPv6 request packet,  it
                   changes  the  packet  into a DHCPv6 reply, replaces the op‐
                   tions by those specified as parameters, and stores 1 in R.

                   When this action is applied to a non-DHCPv6  packet  or  an
                   invalid  DHCPv6  request  packet,  it leaves the packet un‐
                   changed and stores 0 in R.

                   The contents of the DHCPv6_Options table control the DHCPv6
                   option names and values that this action supports.

                   Example:  reg0[3]  =  put_dhcpv6_opts(ia_addr  =   aef0::4,
                   server_id                =               00:00:00:00:10:02,
                   dns_server={ae70::1,ae70::2});

              set_queue(queue_number);
                   Parameters: Queue number queue_number, in the  range  0  to
                   61440.

                   This  is a logical equivalent of the OpenFlow set_queue ac‐
                   tion. It affects packets that egress a hypervisor through a
                   physical interface. For nonzero queue_number, it configures
                   packet queuing to match the  settings  configured  for  the
                   Port_Binding     with    options:qdisc_queue_id    matching
                   queue_number. When queue_number is zero, it resets  queuing
                   to the default strategy.

                   Example: set_queue(10);

              ct_lb_mark;
              ct_lb_mark(backends=ip[:port][,...][;
              hash_fields=field1,field2,...][; ct_flag]);
                   With  arguments,  ct_lb_mark commits the packet to the con‐
                   nection tracking table and DNATs the  packet’s  destination
                   IP  address  (and port) to the IP address or addresses (and
                   optional ports) specified  in  the  backends.  If  multiple
                   comma-separated  IP  addresses are specified, each is given
                   equal weight for picking  the  DNAT  address.  By  default,
                   dp_hash is used as the OpenFlow group selection method, but
                   if  hash_fields is specified, hash is used as the selection
                   method, and the fields listed are used as the hash  fields.
                   The   ct_flag  field  represents  one  of  supported  flag:
                   skip_snat or  force_snat,  this  flag  will  be  stored  in
                   ct_mark register.

                   Without  arguments, ct_lb_mark sends the packet to the con‐
                   nection tracking table to NAT the packets. If the packet is
                   part of an established connection that was previously  com‐
                   mitted  to  the  connection tracker via ct_lb_mark(...), it
                   will automatically get DNATed to the same IP address as the
                   first packet in that connection.

                   Processing automatically moves on to the next table, as  if
                   next; were specified, and later tables act on the packet as
                   modified  by  the  connection  tracker. Connection tracking
                   state is scoped by the logical port when the action is used
                   in a flow for a logical switch,  so  overlapping  addresses
                   may  be  used.  Connection  tracking state is scoped by the
                   logical topology when the action is used in a  flow  for  a
                   router.

              ct_lb_mark_local;
              ct_lb_mark_local(backends=lport_name[ip[:port][,...][;
              hash_fields=field1,field2,...][; ct_flag]);
                   Same  as ct_lb_mark, with the key difference that it imple‐
                   ments local-only load balancing. This mode selects backends
                   only from those running on the current chassis,  preventing
                   traffic from being forwarded to backends on remote nodes.

              R = dns_lookup();
                   Parameters: No parameters.

                   Result: stored to a 1-bit subfield R.

                   Valid only in the ingress pipeline.

                   When  this  action is applied to a valid DNS request (a UDP
                   packet typically directed to port 53), it attempts  to  re‐
                   solve  the query using the contents of the DNS table. If it
                   is successful, it changes the packet into a DNS  reply  and
                   stores  1  in  R.  If  the  action  is applied to a non-DNS
                   packet, an invalid DNS request packet, or a valid  DNS  re‐
                   quest for which the DNS table does not supply an answer, it
                   leaves the packet unchanged and stores 0 in R.

                   Regardless  of success, the action does not make any of the
                   changes to the flow that are necessary to direct the packet
                   back to the requester. The logical pipeline  can  implement
                   this behavior with matches and actions in later tables.

                   Example: reg0[3] = dns_lookup();

                   Prerequisite: udp

              R = put_nd_ra_opts(D1 = V1, D2 = V2, ..., Dn = Vn);
                   Parameters:  The following IPv6 ND Router Advertisement op‐
                   tion/value pairs as defined in RFC 4861.

                   •      addr_mode

                          Mandatory parameter which specifies the address mode
                          flag to be set in the RA  flag  options  field.  The
                          value  of  this option is a string and the following
                          values can be defined -  "slaac",  "dhcpv6_stateful"
                          and "dhcpv6_stateless".

                   •      slla

                          Mandatory  parameter  which specifies the link-layer
                          address of the interface from which the  Router  Ad‐
                          vertisement is sent.

                   •      mtu

                          Optional parameter which specifies the MTU.

                   •      prefix

                          Optional  parameter which should be specified if the
                          addr_mode  is  "slaac"  or  "dhcpv6_stateless".  The
                          value  should  be  an IPv6 prefix which will be used
                          for stateless IPv6 address configuration.  This  op‐
                          tion can be defined multiple times.

                   Result: stored to a 1-bit subfield R.

                   Valid only in the ingress pipeline.

                   When  this action is applied to an IPv6 Router solicitation
                   request packet, it changes the packet into an  IPv6  Router
                   Advertisement  reply  and adds the options specified in the
                   parameters, and stores 1 in R.

                   When this action is applied to a non-IPv6 Router  solicita‐
                   tion  packet  or  an invalid IPv6 request packet, it leaves
                   the packet unchanged and stores 0 in R.

                   Example: reg0[3] = put_nd_ra_opts(addr_mode = "slaac", slla
                   = 00:00:00:00:10:02, prefix = aef0::/64, mtu = 1450);

              set_meter(rate);
              set_meter(rate, burst);
                   Parameters: rate limit int field rate in kbps,  burst  rate
                   limits int field burst in kbps.

                   This action sets the rate limit for a flow.

                   Example: set_meter(100, 1000);

              R = check_pkt_larger(L)
                   Parameters: packet length L to check for in bytes.

                   Result: stored to a 1-bit subfield R.

                   This    is   a   logical   equivalent   of   the   OpenFlow
                   check_pkt_larger action. If the packet is larger  than  the
                   length specified in L, it stores 1 in the subfield R.

                   Example: reg0[6] = check_pkt_larger(1000);

              log(key=value, ...);
                     Causes  ovn-controller  to  log the packet on the chassis
                     that processes it. Packet logging currently uses the same
                     logging mechanism as other Open vSwitch and OVN messages,
                     which means that whether and where  log  messages  appear
                     depends  on  the  local logging configuration that can be
                     configured with ovn-appctl, etc.

                     The log action takes zero or more of the  following  key-
                     value pair arguments that control what is logged:

                     name=string
                            An  optional  name for the ACL. The string is cur‐
                            rently limited to 64 bytes.

                     severity=level
                            Indicates the severity of the event. The level  is
                            one  of  following  (from  more  to less serious):
                            alert, warning,  notice,  info,  or  debug.  If  a
                            severity is not provided, the default is info.

                     verdict=value
                            The  verdict  for  packets  matching the flow. The
                            value must be one of allow, deny, or reject.

                     meter=string
                            An optional rate-limiting meter to be  applied  to
                            the logs. The string should reference a name entry
                            from  the  Meter table. The only meter action that
                            is appropriate is drop.

              fwd_group(liveness=bool, childports=port, ...);
                     Parameters: optional liveness, either true or false,  de‐
                     faulting  to false; childports, a comma-delimited list of
                     strings denoting logical ports to load balance across.

                     Load balance traffic to one or more child ports in a log‐
                     ical switch. ovn-controller translates the fwd_group into
                     an OpenFlow group with one bucket for each child port. If
                     liveness=true is specified, it also integrates the bucket
                     selection with BFD status on the tunnel interface  corre‐
                     sponding to child port.

                     Example: fwd_group(liveness=true, childports="p1", "p2");

              icmp4 { action; ... };
              icmp4_error { action; ... };
                   Temporarily  replaces the IPv4 packet being processed by an
                   ICMPv4 packet and executes each nested action on the ICMPv4
                   packet. Actions following these actions, if any,  apply  to
                   the original, unmodified packet.

                   The  ICMPv4  packet  that these actions operates on is ini‐
                   tialized based on the IPv4 packet being processed, as  fol‐
                   lows. These are default values that the nested actions will
                   probably  want  to  change.  Ethernet  and  IPv4 fields not
                   listed here are not changed:

                   •      ip.proto = 1 (ICMPv4)

                   •      ip.frag = 0 (not a fragment)

                   •      ip.ttl = 255icmp4.type = 3 (destination unreachable)

                   •      icmp4.code = 1 (host unreachable)

                   icmp4_error action is expected to be used  to  generate  an
                   ICMPv4  packet  in  response  to  an  error  in original IP
                   packet. When this action generates the  ICMPv4  packet,  it
                   also  copies  the original IP datagram following the ICMPv4
                   header as per RFC 1122: 3.2.2.

                   Prerequisite: ip4

              icmp6 { action; ... };
              icmp6_error { action; ... };
                   Temporarily replaces the IPv6 packet being processed by  an
                   ICMPv6 packet and executes each nested action on the ICMPv6
                   packet.  Actions  following the icmp6 action, if any, apply
                   to the original, unmodified packet.

                   The ICMPv6 packet that this action operates on is  initial‐
                   ized  based on the IPv6 packet being processed, as follows.
                   These are default values that the nested actions will prob‐
                   ably want to change. Ethernet and IPv6  fields  not  listed
                   here are not changed:

                   •      ip.proto = 58 (ICMPv6)

                   •      ip.ttl = 255icmp6.type = 1 (destination unreachable)

                   •      icmp6.code = 1 (administratively prohibited)

                   icmp6_error  action  is  expected to be used to generate an
                   ICMPv6 packet in response to  an  error  in  original  IPv6
                   packet.

                   Prerequisite: ip6

              tcp_reset { action; ... };
                    This action transforms the current TCP packet according to
                   the following pseudocode:

                   if (tcp.ack) {
                           tcp.seq = tcp.ack;
                   } else {
                           tcp.ack = tcp.seq + length(tcp.payload);
                           tcp.seq = 0;
                   }
                   tcp.flags = RST;

                   Then,  the  action  drops all TCP options and payload data,
                   and updates the TCP checksum. IP ttl is  set  to  255.  The
                   nested actions are executed on the resulting RST packet.

                   Prerequisite: tcp

              sctp_abort { action; ... };
                     This  action  transforms  the current SCTP packet into an
                   ABORT chunk. The nested actions, such as output,  are  exe‐
                   cuted on the resulting ABORT packet.

                   Prerequisite: sctp

              reject { action; ... };
                   If  the  original packet is IPv4 or IPv6 TCP packet, it re‐
                   places it with IPv4 or IPv6 TCP RST packet and executes the
                   inner actions. Otherwise it replaces it with an  ICMPv4  or
                   ICMPv6 packet and executes the inner actions.

                   The  inner  actions  should  not attempt to swap eth source
                   with eth destination and IP source with IP  destination  as
                   this action implicitly does that.

              trigger_event(event = "event_type", ...);
                     This  action  is used to allow ovs-vswitchd to report CMS
                   related events writing them in the Controller_Event  table.
                   It  is possible to associate a meter to each event in order
                   to not overload pinctrl thread under heavy load; each meter
                   is identified though a defined naming convention. Supported
                   events:

                   •      empty_lb_backends. This event is  raised  if  a  re‐
                          ceived  packet  is  destined for a load balancer VIP
                          that has no  configured  backend  destinations.  For
                          this  event,  the  event info includes the load bal‐
                          ancer VIP, the load balancer UUID, and the transport
                          protocol. Associated meter: event-elb

              igmp;
                   This action sends the packet to ovn-controller  for  multi‐
                   cast snooping.

                   Prerequisite: igmp

              bind_vport(V, P);
                   Parameters:  logical  port  string field V of type virtual,
                   logical port string field P.

                   Binds the virtual logical port V and sets the chassis  col‐
                   umn  and  virtual_parent  of  the  table Port_Binding. vir‐‐
                   tual_parent is set to P.

              handle_svc_check(P);
                   Parameters: logical port string field P.

                   Handles the service monitor reply received from the VIF  of
                   the  logical  port P. ovn-controller periodically sends out
                   the service monitor packets for the services configured  in
                   the  Service_Monitor table and this action updates the sta‐
                   tus of those services.

                   Example: handle_svc_check(inport);

              handle_dhcpv6_reply;
                   Handle DHCPv6 prefix delegation advertisements/replies from
                   an IPv6 delegation server and manage the prefix  delegation
                   state   machine.   ovn-controller   will   add   an   entry
                   ipv6_ra_pd_list in the options table for  each  prefix  re‐
                   ceived from the delegation server

              handle_bfd_msg();
                   This  action  sends  BFD packets to ovn-controller for pro‐
                   cessing. ovn-controller handles BFD protocol  messages  re‐
                   ceived on tunnel or logical ports.

              flood_remote;
                   This  action  floods  the packet to all remote ports, i.e.,
                   ports that reside on other chassis.

              R = ct_proto();
                   Result: stored to an 8-bit subfield R.

                   This action returns the IP protocol of the conntrack origi‐
                   nal-direction tuple.

                   Example: reg1[16..23] = ct_proto();

              R = select(N1[=W1], N2[=W2], ...);
              R = select(values=(N1[=W1], N2[=W2], ...);
              hash_fields="field1,field2,...");
                   Parameters: Integer N1, N2..., with optional weight W1, W2,
                   ...

                   Result: stored to a logical field or subfield R.

                   Select from a list of integers N1, N2..., each  within  the
                   range 0 ~ 65535, and store the selected one in the field R.
                   There  must  be 2 or more integers listed, each with an op‐
                   tional weight, which is an integer within  the  range  1  ~
                   65535.  If weight is not specified, it defaults to 100. The
                   selection method is based on the  5-tuple  hash  of  packet
                   header.

                   By default, dp_hash is used as the OpenFlow group selection
                   method,  but  if values and hash_fields are specified, hash
                   is used as the selection method, and the fields listed  are
                   used as the hash fields.

                   Processing  automatically moves on to the next table, as if
                   next; were specified. The select action must be put as  the
                   last action of the logical flow when there are multiple ac‐
                   tions (actions put after select will not take effect).

                   Example:  reg8[16..31] = select(1=20, 2=30, 3=50); Example:
                   reg8[16..31]   =    select(values=(1=20,    2=30,    3=50);
                   hash_fields="ip_proto,src_ip,dst_ip");

              R = chk_lb_hairpin();
                   This  action  checks  if the packet under consideration was
                   destined to a load balancer VIP and it is hairpinned, i.e.,
                   after load balancing the destination IP matches the  source
                   IP.  If  it is so, then the 1-bit destination register R is
                   set to 1.

              R = chk_lb_hairpin_reply();
                   This action checks if the  packet  under  consideration  is
                   from  one  of the backend IP of a load balancer VIP and the
                   destination IP is the load balancer VIP. If it is so,  then
                   the 1-bit destination register R is set to 1.

              ct_snat_to_vip;
                   This  action  sends  the  packet  through  the SNAT zone to
                   change the source IP address of the packet to the load bal‐
                   ancer VIP if the original destination IP was load  balancer
                   VIP  and  commits  the connection. This action applies suc‐
                   cessfully only for the hairpinned traffic i.e if the action
                   chk_lb_hairpin returned success. This action  doesn’t  take
                   any arguments and it determines the SNAT IP internally. The
                   packet  is  not  automatically  sent to the next table. The
                   caller has to execute the  next;  action  explicitly  after
                   this action to advance the packet to the next stage.

              R = check_in_port_sec();
                   This action checks if the packet under consideration passes
                   the  inport  port  security checks. If the packet fails the
                   port security checks, then 1 is stored in  the  destination
                   register  R.  Else 0 is stored. The port security values to
                   check are retrieved from the inport logical port.

                   This action should be used in the  ingress  logical  switch
                   pipeline.

                   Example: reg0[15] = check_in_port_sec();

              R = check_out_port_sec();
                   This action checks if the packet under consideration passes
                   the  outport  port security checks. If the packet fails the
                   port security checks, then 1 is stored in  the  destination
                   register  R.  Else 0 is stored. The port security values to
                   check are retrieved from the outport logical port.

                   This action should be used in  the  egress  logical  switch
                   pipeline.

                   Example: reg0[15] = check_out_port_sec();

              commit_ecmp_nh(ipv6);
                   Parameters: IPv4/IPv6 traffic.

                   This  action  translates to an openflow "learn" action that
                   inserts two new flows in tables referenced by table 100 and
                   101.

                   •      Match on the 5-tuple and the expected  next-hop  mac
                          address   in   table  100:  nw_src=ip0,  nw_dst=ip1,
                          ip_proto,tp_src=l4_port0,
                          tp_dst=l4_port1,dl_src=ethaddr and set reg9[5].

                   •      Match on  the  5-tuple  in  table  101:  nw_src=ip1,
                          nw_dst=ip0,        ip_proto,        tp_src=l4_port1,
                          tp_dst=l4_port0 and set reg9[5] to 1

                   This action is applied if the packet arrives via ECMP route
                   or if it is routed via an ECMP route

              R = chk_ecmp_nh_mac();
                   This  action  checks  if  the  packet  under  consideration
                   matches  any flow in table 100. If it is so, then the 1-bit
                   destination register R is set to 1.

              R = chk_ecmp_nh();
                   This  action  checks  if  the  packet  under  consideration
                   matches  any flow in table 101. If it is so, then the 1-bit
                   destination register R is set to 1.

                   commit_lb_aff(vip, backend,  proto,  timeout);  Parameters:
                   load-balancer  virtual  ip:port  vip, load-balancer backend
                   ip:port backend,  load-balancer  protocol  proto,  affinity
                   timeout timeout.

                   This  action  translates to an openflow "learn" action that
                   inserts a new flow in table 102.

                   •      Match on the 4-tuple in table 102: nw_src=ip client,
                          nw_dst=vip ip, ip_proto,  tp_dst=vip  port  and  set
                          reg9[6]  to  1, reg4 and reg8 to backend ip and port
                          respectively. For IPv6 register xxreg1  is  used  to
                          store the backend ip.

                   This  action  is  applied for new connections received by a
                   specific load-balancer with affinity timeout configured.

              R = chk_lb_aff();
                   This  action  checks  if  the  packet  under  consideration
                   matches  any flow in table 102. If it is so, then the 1-bit
                   destination register R is set to 1.

              R = ct_nw_dst();
                   This action checks if the packet is tracked and stores  the
                   conntrack original destination IPv4 address in the register
                   R of 32-bit size.

              R = ct_ip6_dst();
                   This  action checks if the packet is tracked and stores the
                   conntrack original destination IPv6 address in the register
                   R of 128-bit size.

              R = ct_tp_dst();
                   This action checks if the packet is tracked and stores  the
                   conntrack original L4 destination port in the register R of
                   16-bit size.

              R = ct_state_save();
                   This  action checks if the packet is tracked and stores the
                   conntrack original state in the 8-bit register R.

              sample(probability=packets, ...)
                   This action causes the matched traffic to be sampled  using
                   IPFIX  protocol.  More information about how per-flow IPFIX
                   sampling works in OVS can be found  in  ovs-actions(7)  and
                   ovs-vswitchd.conf.db(5).

                   In  order  to reliably identify each sampled packet when it
                   is received by the IPFIX collector, this  action  sets  the
                   content  of  the ObservationDomainID and ObservationPointID
                   IPFIX fields (see argument description below).

                   The following key-value arguments are supported:

                   probability=packets
                          The number of sampled packets out of 65535. It  must
                          be greater or equal to 1.

                   collector_set=id
                          The unsigned 32-bit integer identifier of the sample
                          collector  to send sampled packets to. It must match
                          the  value  configured  in  the  Flow_Sample_Collec‐‐
                          tor_Set Table in OVS. Defaults to 0.

                   obs_domain=id
                          An  unsigned  8-bit integer that identifies the sam‐
                          pling application. It will be placed in the  8  most
                          significant bits of the ObservationDomainID field of
                          IPFIX  samples. The 24 less significant bits will be
                          automatically filled in with the datapath  key.  De‐
                          faults to 0.

                   obs_point=id
                          An  unsigned  32-bit  integer to be used as Observa‐‐
                          tionPointID or the string @cookie to  indicate  that
                          the  first  32 bits of the Logical_Flow’s UUID shall
                          be used instead.

              mac_cache_use;
                   This action resubmits to corresponding table which  updates
                   the use statistics of MAC cache.

              R = dhcp_relay_req_chk(relay-ip,
                   server-ip);  Parameters:  Logical  Router Port IP relay-ip,
                   DHCP Server IP server-ip.

                   Result: stored to a 1-bit subfield R.

                   This action executes on the source node on which  the  DHCP
                   request (DHCPDISCOVER or DHCPREQUEST) originated.

                   When  this  action applied successfully on the DHCP request
                   packet, it updates GIADDR in the DHCP packet with  relay-ip
                   and stores 1 in R.

                   When  this  action failed to apply on the packet, it leaves
                   the packet unchanged and stores 0 in R.

              R = dhcp_relay_resp_chk(relay-ip,
                   server-ip); Parameters: Logical Router  Port  IP  relay-ip,
                   DHCP Server IP server-ip.

                   Result: stored to a 1-bit subfield R.

                   This  action  executes  on the first node (Redirect Chassis
                   node) which processes the DHCP response(DHCPOFFER, DHCPACK)
                   from the DHCP server.

                   When this action applied successfully on the DHCP  response
                   packet,  it  updates the destination MAC and destination IP
                   in the packet and stores 1 in R. relay-ip and server-ip are
                   used to validate GIADDR and SERVER-ID in the DHCP  response
                   packet.

                   When  this  action failed to apply on the packet, it leaves
                   the packet unchanged and stores 0 in R.

              mirror(P);
                   Parameters: logical port string field P of type mirror.

                   When using an lport mirror, it clones the packet  and  out‐
                   puts  it  to  the local/remote chassis through the mirrored
                   port P to the target port.

       tags: map of string-string pairs
              Key-value pairs that provide additional information to help ovn-
              controller processing the logical flow. Below are the tags  used
              by ovn-controller.

              in_out_port
                     In the logical flow’s "match" column, if a logical port P
                     is  compared  with  "inport" and the logical flow is on a
                     logical switch ingress pipeline, or if P is compared with
                     "outport" and the logical flow is  on  a  logical  switch
                     egress  pipeline,  and  the  expression  is combined with
                     other expressions (if any) using the  operator  &&,  then
                     the  port  P should be added as the value in this tag. If
                     there are multiple logical ports meeting  this  criteria,
                     one of them can be added. ovn-controller uses this infor‐
                     mation  to  skip parsing flows that are not needed on the
                     chassis. Failing to add the tag will  affect  efficiency,
                     while adding wrong value will affect correctness.

       controller_meter: optional string
              The  name of the meter in table Meter to be used for all packets
              that the logical flow might send to ovn-controller.

       flow_desc: optional string
              Human-readable explanation of the flow,  this  is  optional  and
              used to provide context for the given flow.

       external_ids : stage-name: optional string
              Human-readable name for this flow’s stage in the pipeline.

       external_ids : stage-hint: optional string, containing an uuid
              UUID  of  an OVN_Northbound record that caused this logical flow
              to be created.

       external_ids : source: optional string
              Source file and line number of the code that added this flow  to
              the pipeline.

     Common Columns:

       The  overall purpose of these columns is described under Common Columns
       at the beginning of this document.

       external_ids: map of string-string pairs
Logical_DP_Group TABLE
       Each row in this table represents a group of logical  datapaths  refer‐
       enced by the logical_dp_group column in the Logical_Flow table.

   Summary:
       datapaths                     set  of  weak reference to Datapath_Bind‐‐
                                     ings

   Details:
       datapaths: set of weak reference to Datapath_Bindings
              List of Datapath_Binding entries.

Multicast_Group TABLE
       The rows in this table define multicast groups of logical ports. Multi‐
       cast groups allow a single packet transmitted over a tunnel to a hyper‐
       visor to be delivered to multiple VMs on that  hypervisor,  which  uses
       bandwidth more efficiently.

       Each  row in this table defines a logical multicast group numbered tun‐‐
       nel_key within datapath, whose logical ports are listed  in  the  ports
       column.

   Summary:
       datapath                      Datapath_Binding
       tunnel_key                    integer, in range 32,768 to 65,535
       name                          string
       ports                         set of weak reference to Port_Bindings

   Details:
       datapath: Datapath_Binding
              The logical datapath in which the multicast group resides.

       tunnel_key: integer, in range 32,768 to 65,535
              The  value  used to designate this logical egress port in tunnel
              encapsulations. An index forces the key to be unique within  the
              datapath.  The unusual range ensures that multicast group IDs do
              not overlap with logical port IDs.

       name: string
              The logical multicast group’s name. An index forces the name  to
              be  unique  within  the  datapath.  Logical flows in the ingress
              pipeline may output to the group just as for individual  logical
              ports, by assigning the group’s name to outport and executing an
              output action.

              Multicast  group  names  and  logical  port names share a single
              namespace and thus should not overlap (but the  database  schema
              cannot enforce this). To try to avoid conflicts, ovn-northd uses
              names that begin with _MC_.

       ports: set of weak reference to Port_Bindings
              The  logical ports included in the multicast group. All of these
              ports must be in the datapath logical datapath (but the database
              schema cannot enforce this).

Mirror TABLE
       Each row in this table represents a mirror that can be  used  for  port
       mirroring.  These  mirrors are referenced by the mirror_rules column in
       the Port_Binding table.

   Summary:
       name                          string (must be unique within table)
       filter                        string,  one  of  both,  from-lport,   or
                                     to-lport
       sink                          string
       type                          string,  one  of  erspan,  gre, local, or
                                     lport
       index                         integer
       external_ids                  map of string-string pairs

   Details:
       name: string (must be unique within table)
              Represents the name of the mirror.

       filter: string, one of both, from-lport, or to-lport
              The value of this field represents  selection  criteria  of  the
              mirror.  to-lport  mirrors the packets coming into logical port.
              from-lport mirrors the packets going out of logical  port.  both
              mirrors for both directions.

       sink: string
              The  value  of this field represents the destination/sink of the
              mirror. If the type is gre or erspan, the  value  indicates  the
              tunnel  remote  IP  (either  IPv4 or IPv6). For a type of local,
              this field defines a local  interface  on  the  OVS  integration
              bridge  to be used as the mirror destination. The interface must
              possess external-ids:mirror-id that matches this string.

       type: string, one of erspan, gre, local, or lport
              The value of this field specifies the mirror type - gre, erspan,
              local or lport.

       index: integer
              The value of this field represents the tunnel ID. If the config‐
              ured tunnel type is gre, this field represents the GRE key value
              and if the configured tunnel type is erspan  it  represents  the
              erspan_idx value. It is ignored if the type is local.

       external_ids: map of string-string pairs
              See External IDs at the beginning of this document.

Meter TABLE
       Each  row  in this table represents a meter that can be used for QoS or
       rate-limiting.

   Summary:
       name                          string (must be unique within table)
       unit                          string, either kbps or pktps
       bands                         set of 1 or more Meter_Bands

   Details:
       name: string (must be unique within table)
              A name for this meter.

              Names that begin with "__" (two underscores)  are  reserved  for
              OVN internal use and should not be added manually.

       unit: string, either kbps or pktps
              The  unit for rate and burst_size parameters in the bands entry.
              kbps specifies kilobits per second, and pktps specifies  packets
              per second.

       bands: set of 1 or more Meter_Bands
              The bands associated with this meter. Each band specifies a rate
              above  which  the band is to take the action action. If multiple
              bands’ rates are exceeded, then the band with the  highest  rate
              among the exceeded bands is selected.

Meter_Band TABLE
       Each row in this table represents a meter band which specifies the rate
       above  which  the  configured action should be applied. These bands are
       referenced by the bands column in the Meter table.

   Summary:
       action                        string, must be drop
       rate                          integer, in range 1 to 4,294,967,295
       burst_size                    integer, in range 0 to 4,294,967,295

   Details:
       action: string, must be drop
              The action to execute when this band matches. The only supported
              action is drop.

       rate: integer, in range 1 to 4,294,967,295
              The rate limit for this band, in kilobits per second or  packets
              per  second,  depending on whether the parent Meter entry’s unit
              column specified kbps or pktps.

       burst_size: integer, in range 0 to 4,294,967,295
              The maximum burst allowed for the band in kilobits  or  packets,
              depending  on  whether  kbps or pktps was selected in the parent
              Meter entry’s unit column. If the size is zero,  the  switch  is
              free to select some reasonable value depending on its configura‐
              tion.
Datapath_Binding TABLE
       Each  row in this table represents a logical datapath, which implements
       a logical pipeline among the ports in the Port_Binding table associated
       with it. In practice, the pipeline in a given logical  datapath  imple‐
       ments either a logical switch or a logical router.

       The  main purpose of a row in this table is to provide a physical bind‐
       ing for a logical datapath. A logical datapath does not have a physical
       location, so its physical binding information  is  limited:  just  tun‐‐
       nel_key. The rest of the data in this table does not affect packet for‐
       warding.

   Summary:
       tunnel_key                    integer,  in  range 1 to 16,777,215 (must
                                     be unique within table)
       load_balancers                set of uuids
       OVN_Northbound Relationship:
         type                        optional string, either logical-router or
                                     logical-switch
         nb_uuid                     optional uuid
         external_ids : interconn-ts
                                     optional string
         Naming:
            external_ids : name      optional string
            external_ids : name2     optional string
       Common Columns:
         external_ids                map of string-string pairs

   Details:
       tunnel_key: integer, in range 1 to 16,777,215 (must be unique within
       table)
              The tunnel key value to which the logical datapath is bound. The
              Tunnel Encapsulation section  in  ovn-architecture(7)  describes
              how  tunnel  keys  are constructed for each supported encapsula‐
              tion.

       load_balancers: set of uuids
              Not used  anymore;  kept  for  backwards  compatibility  of  the
              schema.

     OVN_Northbound Relationship:

       Each  row in Datapath_Binding is associated with some logical datapath.
       ovn-northd uses these keys to track the association of a logical  data‐
       path with concepts in the OVN_Northbound database.

       type: optional string, either logical-router or logical-switch
              This represents the type of the northbound logical datapath that
              is represented by this southbound Datapath_Binding. The possible
              values for this are:

              •      logical-switchlogical-router

       nb_uuid: optional uuid
              This  is  the UUID of the corresponding northbound logical data‐
              path represented by this southbound Datapath_Binding.

       external_ids : interconn-ts: optional string
              For a logical datapath that represents  a  logical  switch  that
              represents  a  transit  switch  for  interconnection, ovn-northd
              stores in this key the value of the same interconn-ts key of the
              external_ids column of the corresponding Logical_Switch  row  in
              the OVN_Northbound database.

     Naming:

       ovn-northd  copies  these  from  the  name fields in the OVN_Northbound
       database, either from name and external_ids:neutron:router_name in  the
       Logical_Router table or from name and external_ids:neutron:network_name
       in the Logical_Switch table.

       external_ids : name: optional string
              A name for the logical datapath.

       external_ids : name2: optional string
              Another name for the logical datapath.

     Common Columns:

       The  overall purpose of these columns is described under Common Columns
       at the beginning of this document.

       external_ids: map of string-string pairs
Port_Binding TABLE
       Each row in this table binds a logical port to a realization. For  most
       logical  ports, this means binding to some physical location, for exam‐
       ple by binding a logical port to a VIF that belongs to a VM running  on
       a  particular  hypervisor.  Other  logical ports, such as logical patch
       ports, can be realized without a specific physical location, but  their
       bindings are still expressed through rows in this table.

       For   every  Logical_Switch_Port  record  in  OVN_Northbound  database,
       ovn-northd creates a record in this  table.  ovn-northd  populates  and
       maintains  every  column except the chassis and virtual_parent columns,
       which it leaves empty in new records.

       ovn-controller/ovn-controller-vtep populates the chassis column for the
       records that identify the logical ports that are located on its  hyper‐
       visor/gateway,  which  ovn-controller/ovn-controller-vtep in turn finds
       out by monitoring the local hypervisor’s Open_vSwitch  database,  which
       identifies  logical  ports  via  the  conventions described in Integra‐‐
       tionGuide.rst. (The exceptions are for Port_Binding records  with  type
       of  l3gateway, whose locations are identified by ovn-northd via the op‐‐
       tions:l3gateway-chassis column in this table. ovn-controller  is  still
       responsible to populate the chassis column.)

       ovn-controller  also  populates  the  virtual_parent  column of records
       whose type is virtual.

       When a chassis shuts down gracefully, it should clean  up  the  chassis
       column  that it previously had populated. (This is not critical because
       resources hosted on the chassis are equally unreachable  regardless  of
       whether  their rows are present.) To handle the case where a VM is shut
       down abruptly on one chassis, then brought up again on a different one,
       ovn-controller/ovn-controller-vtep must overwrite  the  chassis  column
       with new information.

   Summary:
       Core Features:
         datapath                    Datapath_Binding
         logical_port                string (must be unique within table)
         encap                       optional weak reference to Encap
         additional_encap            set of weak reference to Encaps
         chassis                     optional weak reference to Chassis
         additional_chassis          set of weak reference to Chassis
         gateway_chassis             set of Gateway_Chassises
         ha_chassis_group            optional HA_Chassis_Group
         up                          optional boolean
         tunnel_key                  integer, in range 1 to 32,767
         mac                         set of strings
         port_security               set of strings
         mirror_port                 optional string
         type                        string
         requested_chassis           optional weak reference to Chassis
         requested_additional_chassis
                                     set of weak reference to Chassis
       mirror_rules                  set of weak reference to Mirrors
       Patch Options:
         options : peer              optional string
         nat_addresses               set of strings
       L3 Gateway Options:
         options : peer              optional string
         options : l3gateway-chassis
                                     optional string
         nat_addresses               set of strings
       Localnet Options:
         options : network_name      optional string
         tag                         optional integer, in range 1 to 4,095
       L2 Gateway Options:
         options : network_name      optional string
         options : l2gateway-chassis
                                     optional string
         tag                         optional integer, in range 1 to 4,095
       VTEP Options:
         options : vtep-physical-switch
                                     optional string
         options : vtep-logical-switch
                                     optional string
       VMI (or VIF) Options:
         options : requested-chassis
                                     optional string
         options : requested-encap-ip
                                     optional string
         options : activation-strategy
                                     optional string
         options : additional-chassis-activated
                                     optional string
         options : iface-id-ver      optional string
         options : qos_min_rate      optional string
         options : qos_max_rate      optional string
         options : qos_burst         optional string
         options : qos_physical_network
                                     optional string
         options : qdisc_queue_id    optional  string,  containing an integer,
                                     in range 1 to 61,440
         options : dynamic-routing-advertise
                                     optional string
       Distributed Gateway Port Options:
         options : chassis-redirect-port
                                     optional string
       Chassis Redirect Options:
         options : distributed-port  optional string
         options : redirect-type     optional string
         options : always-redirect   optional string
       Dynamic Routing:
         options : dynamic-routing   optional string, either true or false
         options : dynamic-routing-maintain-vrf
                                     optional string, either true or false
         options : dynamic-routing-vrf-name
                                     optional string
         options : dynamic-routing-port-name
                                     optional string
         options : dynamic-routing-redistribute-local-only
                                     optional string, either true or false
         options : dynamic-routing-no-learning
                                     optional string, either true or false
       Nested Containers:
         parent_port                 optional string
         tag                         optional integer, in range 1 to 4,095
       Virtual ports:
         virtual_parent              optional string
       Naming:
         external_ids : name         optional string
       Common Columns:
         external_ids                map of string-string pairs

   Details:
     Core Features:

       datapath: Datapath_Binding
              The logical datapath to which the logical port belongs.

       logical_port: string (must be unique within table)
              A logical port. For a logical switch port, this  is  taken  from
              name in the OVN_Northbound database’s Logical_Switch_Port table.
              For  a  logical  router  port,  this  is  taken from name in the
              OVN_Northbound database’s Logical_Router_Port table. (This means
              that logical switch ports and router port names must  not  share
              names in an OVN deployment.) OVN does not prescribe a particular
              format for the logical port ID.

       encap: optional weak reference to Encap
              Points to preferred encapsulation configuration to transmit log‐
              ical dataplane packets to this chassis. The entry is a reference
              to a Encap record.

       additional_encap: set of weak reference to Encaps
              Points to preferred encapsulation configuration to transmit log‐
              ical  dataplane packets to this additional chassis. The entry is
              a reference to a Encap record. See also additional_chassis.

       chassis: optional weak reference to Chassis
              The meaning of this column depends on the value of the type col‐
              umn. This is the meaning for each type

              (empty string)
                     The physical location of the logical  port.  To  success‐
                     fully  identify  a chassis, this column must be a Chassis
                     record. This is populated by ovn-controller.

              vtep   The physical location of the  hardware_vtep  gateway.  To
                     successfully  identify  a  chassis, this column must be a
                     Chassis record. This is populated by ovn-controller-vtep.

              localnet
                     Always empty. A localnet port is realized on every  chas‐
                     sis  that  has connectivity to the corresponding physical
                     network.

              localport
                     Always empty. A localport port is present on every  chas‐
                     sis.

              l3gateway
                     The  physical location of the L3 gateway. To successfully
                     identify a chassis, this column must be a Chassis record.
                     This is populated by ovn-controller based on the value of
                     the options:l3gateway-chassis column in this table.

              l2gateway
                     The physical location of this L2 gateway. To successfully
                     identify a chassis, this column must be a Chassis record.
                     This is populated by ovn-controller based on the value of
                     the options:l2gateway-chassis column in this table.

              external
                     A logical port representing an externally  connected  en‐
                     tity.  An external port requires a ha_chassis_group and a
                     localnet port on the same  logical  switch  to  be  func‐
                     tional.  ovn-northd  syncs  the HA chassis group from the
                     corresponding Logical_Switch_Port and  generates  logical
                     flows  that  direct  traffic through the localnet port on
                     the bound chassis. Without a ha_chassis_group, no logical
                     flows are generated for the port.

              remote A logical router port whose  peer  resides  on  a  remote
                     chassis  (one whose other_config:is-remote is true). This
                     type is set instead of patch when  ovn-northd  determines
                     that the requested chassis is remote.

              mirror A  synthetic port binding created for lport-level mirror‐
                     ing. It acts similarly to a container port (without  VLAN
                     tagging)  and  has its mirror_port column set to point to
                     the mirror target port.

       additional_chassis: set of weak reference to Chassis
              The meaning of this column is the same as for the  chassis.  The
              column  is  used to track an additional physical location of the
              logical port. Used with regular (empty type) port bindings.

       gateway_chassis: set of Gateway_Chassises
              A list of Gateway_Chassis.

              This should only be populated for ports with type set  to  chas‐‐
              sisredirect.  This  column  defines  the list of chassis used as
              gateways where traffic will be redirected through.

       ha_chassis_group: optional HA_Chassis_Group
              A list of HA chassis for this port binding. It is populated  for
              ports with type set to chassisredirect or external.

              For  chassisredirect  ports, the HA chassis are used as gateways
              where traffic will be redirected through.

              For external ports, the HA chassis group determines which  chas‐
              sis  binds  the  port and handles its traffic through a localnet
              port on the same logical switch.

       up: optional boolean
              This is set to true whenever all  OVS  flows  required  by  this
              Port_Binding  have been installed. This is populated by ovn-con‐‐
              troller.

       tunnel_key: integer, in range 1 to 32,767
              A number that represents the logical port in the key (e.g.  Gen‐
              eve TLV) field carried within tunnel protocol packets.

              The tunnel ID must be unique within the scope of a logical data‐
              path.

       mac: set of strings
              This column is a misnomer as it may contain MAC addresses and IP
              addresses.  It  is copied from the addresses column in the Logi‐‐
              cal_Switch_Port table in the Northbound database. It follows the
              same format as that column.

       port_security: set of strings
              This column controls the addresses from which the host  attached
              to  the  logical  port (``the host’’) is allowed to send packets
              and to which it is allowed to receive packets. If this column is
              empty, all addresses are permitted.

              It  is  copied  from  the  port_security  column  in  the  Logi‐‐
              cal_Switch_Port table in the Northbound database. It follows the
              same format as that column.

       mirror_port: optional string
              Points to mirror target port fot lport mirror type.

       type: string
              A type for this logical port. Logical ports can be used to model
              other types of connectivity into an OVN logical switch. The fol‐
              lowing types are defined:

              (empty string)
                     VM (or VIF) interface.

              patch  One  of  a pair of logical ports that act as if connected
                     by a patch cable. Useful for connecting two logical data‐
                     paths, e.g. to connect a  logical  router  to  a  logical
                     switch or to another logical router.

              l3gateway
                     One  of  a pair of logical ports that act as if connected
                     by a patch cable across multiple chassis. Useful for con‐
                     necting a logical switch with a Gateway router (which  is
                     only resident on a particular chassis).

              localnet
                     A   connection  to  a  locally  accessible  network  from
                     ovn-controller instances that have a corresponding bridge
                     mapping. A logical  switch  can  have  multiple  localnet
                     ports attached. This type is used to model direct connec‐
                     tivity  to  existing networks. In this case, each chassis
                     should have a mapping for one of  the  physical  networks
                     only.  Note:  nothing  said  above implies that a chassis
                     cannot be plugged to multiple physical networks  as  long
                     as they belong to different switches.

              localport
                     A  connection  to  a local VIF. Traffic that arrives on a
                     localport is never forwarded over  a  tunnel  to  another
                     chassis.  These  ports  are  present on every chassis and
                     have the same address in all of them.  This  is  used  to
                     model  connectivity  to  local services that run on every
                     hypervisor.

              l2gateway
                     An L2 connection to a physical network. The chassis  this
                     Port_Binding  is  bound to will serve as an L2 gateway to
                     the network named by options:network_name.

              vtep   A port to a logical switch on a VTEP gateway chassis.  In
                     order  to  get  this port correctly recognized by the OVN
                     controller,  the  options:vtep-physical-switch  and   op‐‐
                     tions:vtep-logical-switch must also be defined.

              chassisredirect
                     A  logical  port  that  represents a particular instance,
                     bound to a specific chassis, of an otherwise  distributed
                     parent  port (e.g. of type patch). A chassisredirect port
                     should never be  used  as  an  inport.  When  an  ingress
                     pipeline sets the outport, it may set the value to a log‐
                     ical  port  of  type chassisredirect. This will cause the
                     packet to be directed to a specific chassis to carry  out
                     the  egress  pipeline.  At  the  beginning  of the egress
                     pipeline, the outport will be reset to the value  of  the
                     distributed port.

              virtual
                     Represents  a  logical port with an virtual ip. This vir‐‐
                     tual ip can be configured on a logical port (which is re‐
                     ferred as virtual parent).

       requested_chassis: optional weak reference to Chassis
              This column exists so that the  ovn-controller  can  effectively
              monitor  all Port_Binding records destined for it, and is a sup‐
              plement to the options:requested-chassis option. The  option  is
              still  required so that the ovn-controller can check the CMS in‐
              tent when the chassis pointed to does not currently exist, which
              for example occurs when the ovn-controller  is  stopped  without
              passing  the  -restart  argument.  This column must be a Chassis
              record. This is populated by  ovn-northd  when  the  options:re‐‐
              quested-chassis  is  defined  and contains a string matching the
              name or hostname of an existing chassis. See also  requested_ad‐‐
              ditional_chassis.

       requested_additional_chassis: set of weak reference to Chassis
              This  column  exists  so that the ovn-controller can effectively
              monitor all Port_Binding records destined for it, and is a  sup‐
              plement  to  the  options:requested-chassis option when multiple
              chassis are listed. This  column  must  be  a  list  of  Chassis
              records.  This  is  populated by ovn-northd when the options:re‐‐
              quested-chassis is defined as a list of chassis names  or  host‐
              names. See also requested_chassis.

       mirror_rules: set of weak reference to Mirrors
              Mirror rules that apply to the port binding. Please see the Mir‐‐
              ror table.

     Patch Options:

       These options apply to logical ports with type of patch.

       options : peer: optional string
              The  logical_port  in the Port_Binding record for the other side
              of the patch. The named logical_port  must  specify  this  logi‐‐
              cal_port  in its own peer option. That is, the two patch logical
              ports must have reversed logical_port and peer values.

       nat_addresses: set of strings
              MAC address followed by a list of SNAT and DNAT external IP  ad‐
              dresses,  followed  by is_chassis_resident("lport"), where lport
              is the name of a logical port on the same chassis where the cor‐
              responding NAT rules are applied. This is used  to  send  gratu‐
              itous ARPs for SNAT and DNAT external IP addresses via localnet,
              from the chassis where lport resides. Example: 80:fa:5b:06:72:b7
              158.36.44.22   158.36.44.24   is_chassis_resident("foo1").  This
              would result in generation of gratuitous ARPs for  IP  addresses
              158.36.44.22   and   158.36.44.24   with   a   MAC   address  of
              80:fa:5b:06:72:b7 from the chassis where the logical port "foo1"
              resides.

     L3 Gateway Options:

       These options apply to logical ports with type of l3gateway.

       options : peer: optional string
              The logical_port in the Port_Binding record for the  other  side
              of  the  ’l3gateway’  port.  The named logical_port must specify
              this logical_port in its own  peer  option.  That  is,  the  two
              ’l3gateway’  logical  ports  must have reversed logical_port and
              peer values.

       options : l3gateway-chassis: optional string
              The chassis in which the port resides.

       nat_addresses: set of strings
              MAC address of the l3gateway port followed by a list of SNAT and
              DNAT external IP addresses. This is used to send gratuitous ARPs
              for SNAT and DNAT external IP addresses via  localnet.  Example:
              80:fa:5b:06:72:b7  158.36.44.22  158.36.44.24. This would result
              in generation of gratuitous ARPs for IP  addresses  158.36.44.22
              and  158.36.44.24  with a MAC address of 80:fa:5b:06:72:b7. This
              is used in OVS version 2.8 and later versions.

     Localnet Options:

       These options apply to logical ports with type of localnet.

       options : network_name: optional string
              Required.   ovn-controller   uses   the   configuration    entry
              ovn-bridge-mappings to determine how to connect to this network.
              ovn-bridge-mappings is a list of network names mapped to a local
              OVS  bridge  that provides access to that network. An example of
              configuring ovn-bridge-mappings would be: .IP
              $ ovs-vsctl set open . external-ids:ovn-bridge-mappings=physnet1:br-eth0,physnet2:br-eth1

              When a logical switch has a localnet port attached, every  chas‐
              sis  that  may  have a local vif attached to that logical switch
              must have a bridge mapping configured to  reach  that  localnet.
              Traffic  that arrives on a localnet port is never forwarded over
              a tunnel to another chassis.  If  there  are  multiple  localnet
              ports  in a logical switch, each chassis should only have a sin‐
              gle bridge mapping for one of the physical  networks.  Note:  In
              case  of  multiple  localnet ports, to provide interconnectivity
              between all VIFs located on  different  chassis  with  different
              fabric  connectivity,  the  fabric should implement some form of
              routing between the segments.

       tag: optional integer, in range 1 to 4,095
              If set, indicates that the port represents  a  connection  to  a
              specific  VLAN  on  a locally accessible network. The VLAN ID is
              used to match incoming traffic and is  also  added  to  outgoing
              traffic.

     L2 Gateway Options:

       These options apply to logical ports with type of l2gateway.

       options : network_name: optional string
              Required.    ovn-controller   uses   the   configuration   entry
              ovn-bridge-mappings to determine how to connect to this network.
              ovn-bridge-mappings is a list of network names mapped to a local
              OVS bridge that provides access to that network. An  example  of
              configuring ovn-bridge-mappings would be: .IP
              $ ovs-vsctl set open . external-ids:ovn-bridge-mappings=physnet1:br-eth0,physnet2:br-eth1

              When a logical switch has a l2gateway port attached, the chassis
              that  the  l2gateway port is bound to must have a bridge mapping
              configured to reach the network identified by network_name.

       options : l2gateway-chassis: optional string
              Required. The chassis in which the port resides.

       tag: optional integer, in range 1 to 4,095
              If set, indicates that the gateway is connected  to  a  specific
              VLAN  on  the physical network. The VLAN ID is used to match in‐
              coming traffic and is also added to outgoing traffic.

     VTEP Options:

       These options apply to logical ports with type of vtep.

       options : vtep-physical-switch: optional string
              Required. The name of the VTEP gateway.

       options : vtep-logical-switch: optional string
              Required. A logical switch name connected by the  VTEP  gateway.
              Must be set when type is vtep.

     VMI (or VIF) Options:

       These options apply to logical ports with type having (empty string)

       options : requested-chassis: optional string
              If set, identifies a specific chassis (by name or hostname) that
              is  allowed  to  bind  this port. Using this option will prevent
              thrashing between two chassis trying to bind the same port  dur‐
              ing  a live migration. It can also prevent similar thrashing due
              to a mis-configuration, if a port  is  accidentally  created  on
              more than one chassis.

              If set to a comma separated list, the first entry identifies the
              main  chassis  and  the  rest are one or more additional chassis
              that are allowed to bind the same port.

              When multiple chassis are set for  the  port,  and  the  logical
              switch  is  connected  to an external network through a localnet
              port, tunneling is enforced for the port to  guarantee  delivery
              of  packets  directed to the port to all its locations. This has
              MTU implications because the network  used  for  tunneling  must
              have MTU larger than localnet for stable connectivity.

       options : requested-encap-ip: optional string
              If  set,  ovn-northd resolves and sets encap for this port based
              on the requested tunnel endpoint IP. If  absent,  ovn-controller
              may manage encap from local interface external_ids:encap-ip.

       options : activation-strategy: optional string
              If  used with multiple chassis set in options:requested-chassis,
              specifies an activation strategy for all additional chassis.  By
              default, no activation strategy is used, meaning additional port
              locations are immediately available for use. The option supports
              a  comma  separated  list  where  you  can  combine 3 protocols,
              "rarp", "garp" and "na". When any of the protocols is  set,  the
              port  is  blocked  for  ingress and egress communication until a
              specified protocol packet is sent from a new location. The acti‐
              vation strategy is useful in live migration scenarios  for  vir‐
              tual machines.

       options : additional-chassis-activated: optional string
              When  options:activation-strategy  is set, this option indicates
              that the port was activated using the strategy specified.

       options : iface-id-ver: optional string
              If set, this port will be bound by ovn-controller only  if  this
              same  key  and value is configured in the external_ids column in
              the Open_vSwitch database’s Interface table.

       options : qos_min_rate: optional string
              If set, indicates the minimum guaranteed rate available for data
              sent from this interface, in bit/s.

       options : qos_max_rate: optional string
              If set, indicates the maximum rate for data sent from  this  in‐
              terface,  in bit/s. The traffic will be shaped according to this
              limit.

       options : qos_burst: optional string
              If set, indicates the maximum burst size for data sent from this
              interface, in bits.

       options : qos_physical_network: optional string
              If set, indicates the name of  the  egress  network  name  where
              traffic shaping will be applied.

       options : qdisc_queue_id: optional string, containing an integer, in
       range 1 to 61,440
              Indicates  the queue number on the physical device. This is same
              as the queue_id used in OpenFlow in struct ofp_action_enqueue.

       options : dynamic-routing-advertise: optional string
              If the CMS sets other_config:dynamic-routing-redistribute to fdb
              and/or ip, this parameter is used by the CMS  to  enable/disable
              the advertisement of LSP IPs/MAC binding. Default: true.

     Distributed Gateway Port Options:

       These  options  apply  to the distributed parent ports of logical ports
       with type of chassisredirect.

       options : chassis-redirect-port: optional string
              The name of the chassis redirect port derived from this port  if
              this port is a distributed parent of a chassis redirect port.

     Chassis Redirect Options:

       These options apply to logical ports with type of chassisredirect.

       options : distributed-port: optional string
              The  name of the distributed port for which this chassisredirect
              port represents a particular instance.

       options : redirect-type: optional string
              The value is copied from the column options  in  the  OVN_North‐
              bound  database’s  Logical_Router_Port table for the distributed
              parent of this port.

       options : always-redirect: optional string
              A boolean option that is set to true if the  distributed  parent
              of this chassis redirect port does not need distributed process‐
              ing.

     Dynamic Routing:

       options : dynamic-routing: optional string, either true or false
              Set  to true by ovn-northd on chassisredirect and l3gateway port
              bindings when the parent logical router has dynamic routing  en‐
              abled. This enables ovn-controller to advertise and learn routes
              for this port.

       options : dynamic-routing-maintain-vrf: optional string, either true or
       false
              Only relevant if options:dynamic-routing is set to true.

              When set to true, ovn-controller creates and maintains a VRF for
              this  port’s  routing  protocol  session.  Copied from the Logi‐‐
              cal_Router_Port options:dynamic-routing-maintain-vrf option.

       options : dynamic-routing-vrf-name: optional string
              Only relevant if options:dynamic-routing is set to true.

              The VRF name to use for this port’s  routing  protocol  session.
              Copied  from the Logical_Router options:dynamic-routing-vrf-name
              option.

       options : dynamic-routing-port-name: optional string
              Only relevant if options:dynamic-routing is set to true.

              The port name within the VRF for this  port’s  routing  protocol
              session.   Copied   from   the  Logical_Router_Port  options:dy‐‐
              namic-routing-port-name option.

       options : dynamic-routing-redistribute-local-only: optional string, ei‐
       ther true or false
              Only relevant if options:dynamic-routing is set to true.

              This  controls  whether  ovn-controller  will  advertise  Adver‐‐
              tised_Route records only on the chassis where their tracked_port
              is bound. Default: false.

       options : dynamic-routing-no-learning: optional string, either true or
       false
              Only relevant if options:dynamic-routing is set to true.

              This  option  disables  adding  routes to Learned_Route and will
              also remove learned routes.

     Nested Containers:

       These columns support containers nested within a VM. Specifically, they
       are used when type is empty and logical_port identifies  the  interface
       of  a  container  spawned inside a VM. They are empty for containers or
       VMs that run directly on a hypervisor.

       parent_port: optional string
              This is taken from parent_name in the OVN_Northbound  database’s
              Logical_Switch_Port table.

       tag: optional integer, in range 1 to 4,095
              Identifies  the  VLAN tag in the network traffic associated with
              that container’s network interface.

              This column is used for a different purpose when type is  local‐‐
              net  (see  Localnet Options, above) or l2gateway (see L2 Gateway
              Options, above).

     Virtual ports:

       virtual_parent: optional string
              This column is set by ovn-controller with one of the value  from
              the  options:virtual-parents  in  the  OVN_Northbound database’s
              Logical_Switch_Port table when the OVN action bind_vport is exe‐
              cuted. ovn-controller also sets the chassis column when it  exe‐
              cutes this action with its chassis id.

              ovn-controller sets this column only if the type is "virtual".

     Naming:

       external_ids : name: optional string
              For  a  logical  switch port, ovn-northd copies this from exter‐‐
              nal_ids:neutron:port_name in the  Logical_Switch_Port  table  in
              the OVN_Northbound database, if it is a nonempty string.

              For  a  logical  router  port, ovn-northd does not currently set
              this key.

     Common Columns:

       external_ids: map of string-string pairs
              See External IDs at the beginning of this document.

              The ovn-northd program populates this column  with  all  entries
              into the external_ids column of the Logical_Switch_Port and Log‐‐
              ical_Router_Port tables of the OVN_Northbound database.

MAC_Binding TABLE
       Each  row  in  this  table specifies a binding from an IP address to an
       Ethernet address that has been discovered through  ARP  (for  IPv4)  or
       neighbor discovery (for IPv6). This table is primarily used to discover
       bindings  on  physical networks, because IP-to-MAC bindings for virtual
       machines are usually populated statically into the Port_Binding table.

       This  table  expresses  a  functional  relationship:  MAC_Binding(logi‐‐
       cal_port, ip) = mac.

       In  outline,  the lifetime of a logical router’s MAC binding looks like
       this:

              1.  On hypervisor 1, a logical router determines that  a  packet
                  should  be  forwarded  to  IP address A on one of its router
                  ports. It uses its logical flow table to  determine  that  A
                  lacks  a  static IP-to-MAC binding and the get_arp action to
                  determine that it lacks a dynamic IP-to-MAC binding.

              2.  Using an OVN logical arp action, the logical  router  gener‐
                  ates  and  sends a broadcast ARP request to the router port.
                  It drops the IP packet.

              3.  The logical switch attached to the router port delivers  the
                  ARP request to all of its ports. (It might make sense to de‐
                  liver  it  only to ports that have no static IP-to-MAC bind‐
                  ings, but this could also be surprising behavior.)

              4.  A host or VM on hypervisor 2 (which might be the same as hy‐
                  pervisor 1) attached to the logical switch owns the  IP  ad‐
                  dress  in question. It composes an ARP reply and unicasts it
                  to the logical router port’s Ethernet address.

              5.  The logical switch delivers the ARP  reply  to  the  logical
                  router port.

              6.  The  logical router flow table executes a put_arp action. To
                  record the IP-to-MAC binding, ovn-controller adds a  row  to
                  the MAC_Binding table.

              7.  On   hypervisor   1,  ovn-controller  receives  the  updated
                  MAC_Binding table from the OVN southbound database. The next
                  packet destined to A through the logical router is sent  di‐
                  rectly to the bound Ethernet address.

       In  EVPN deployments, ovn-controller also writes rows to this table for
       MAC bindings learned through EVPN Type-2 routes (via FRR and the kernel
       neighbor table). These entries are keyed by the router  port  connected
       to  the  EVPN  logical  switch and behave identically to ARP/ND-learned
       bindings for consumption and aging purposes.

   Summary:
       logical_port                  string
       ip                            string
       mac                           string
       timestamp                     integer
       datapath                      Datapath_Binding

   Details:
       logical_port: string
              The logical port on which the binding was discovered.

       ip: string
              The bound IP address.

       mac: string
              The Ethernet address to which the IP is bound.

       timestamp: integer
              The timestamp in msec when the MAC binding was added or updated.
              Records that existed before this column will have 0.

       datapath: Datapath_Binding
              The logical datapath to which the logical port belongs.

DHCP_Options TABLE
       Each row in this table stores the DHCP Options supported by native  OVN
       DHCP.  ovn-northd populates this table with the supported DHCP options.
       ovn-controller looks up this table to get the DHCP codes  of  the  DHCP
       options  defined in the "put_dhcp_opts" action. Please refer to the RFC
       2132 "https://tools.ietf.org/html/rfc2132" for  the  possible  list  of
       DHCP options that can be defined here.

   Summary:
       name                          string
       code                          integer, in range 0 to 254
       type                          string,  one  of  bool, domains, host_id,
                                     ipv4, static_routes, str, uint16, uint32,
                                     or uint8

   Details:
       name: string
              Name of the DHCP option.

              Example. name="router"

       code: integer, in range 0 to 254
              DHCP option code for the DHCP option as defined in the RFC 2132.

              Example. code=3

       type: string, one of bool, domains, host_id, ipv4, static_routes, str,
       uint16, uint32, or uint8
              Data type of the DHCP option code.

              value: bool
                     This indicates that the value of the  DHCP  option  is  a
                     bool.

                     Example.       "name=ip_forward_enable",       "code=19",
                     "type=bool".

                     put_dhcp_opts(..., ip_forward_enable = 1,...)

              value: uint8
                     This indicates that the value of the DHCP  option  is  an
                     unsigned int8 (8 bits)

                     Example. "name=default_ttl", "code=23", "type=uint8".

                     put_dhcp_opts(..., default_ttl = 50,...)

              value: uint16
                     This  indicates  that  the value of the DHCP option is an
                     unsigned int16 (16 bits).

                     Example. "name=mtu", "code=26", "type=uint16".

                     put_dhcp_opts(..., mtu = 1450,...)

              value: uint32
                     This indicates that the value of the DHCP  option  is  an
                     unsigned int32 (32 bits).

                     Example. "name=lease_time", "code=51", "type=uint32".

                     put_dhcp_opts(..., lease_time = 86400,...)

              value: ipv4
                     This  indicates  that  the value of the DHCP option is an
                     IPv4 address or addresses.

                     Example. "name=router", "code=3", "type=ipv4".

                     put_dhcp_opts(..., router = 10.0.0.1,...)

                     Example. "name=dns_server", "code=6", "type=ipv4".

                     put_dhcp_opts(..., dns_server = {8.8.8.8 7.7.7.7},...)

              value: static_routes
                     This indicates that the value of the DHCP option contains
                     a pair of IPv4 route and next hop addresses.

                     Example.    "name=classless_static_route",    "code=121",
                     "type=static_routes".

                     put_dhcp_opts(...,        classless_static_route        =
                     {30.0.0.0/24,10.0.0.4,0.0.0.0/0,10.0.0.1}...)

              value: str
                     This indicates that the value of the  DHCP  option  is  a
                     string.

                     Example. "name=host_name", "code=12", "type=str".

              value: host_id
                     This  indicates  that  the  value of the DHCP option is a
                     host_id. It can either be a host_name or an IP address.

                     Example. "name=tftp_server", "code=66", "type=host_id".

              value: domains
                     This indicates that the value of the DHCP option is a do‐
                     main name or a comma separated list of domain names.

                     Example. "name=domain_search_list", "code=119", "type=do‐
                     mains".
DHCPv6_Options TABLE
       Each row in this table stores the DHCPv6 Options  supported  by  native
       OVN  DHCPv6.  ovn-northd populates this table with the supported DHCPv6
       options. ovn-controller looks up this table to get the DHCPv6 codes  of
       the  DHCPv6 options defined in the put_dhcpv6_opts action. Please refer
       to RFC 3315 and RFC 3646 for the list of DHCPv6 options that can be de‐
       fined here.

   Summary:
       name                          string
       code                          integer, in range 0 to 254
       type                          string, one of domain, ipv6, mac, or str

   Details:
       name: string
              Name of the DHCPv6 option.

              Example. name="ia_addr"

       code: integer, in range 0 to 254
              DHCPv6 option code for the DHCPv6 option as defined in  the  ap‐
              propriate RFC.

              Example. code=3

       type: string, one of domain, ipv6, mac, or str
              Data type of the DHCPv6 option code.

              value: ipv6
                     This  indicates that the value of the DHCPv6 option is an
                     IPv6 address(es).

                     Example. "name=ia_addr", "code=5", "type=ipv6".

                     put_dhcpv6_opts(..., ia_addr = ae70::4,...)

              value: str
                     This indicates that the value of the DHCPv6 option  is  a
                     string.

                     Example. "name=domain_search", "code=24", "type=str".

                     put_dhcpv6_opts(..., domain_search = ovn.domain,...)

              value: mac
                     This  indicates  that the value of the DHCPv6 option is a
                     MAC address.

                     Example. "name=server_id", "code=2", "type=mac".

                     put_dhcpv6_opts(..., server_id = 01:02:03:04:05:06,...)

              value: domain
                     This indicates that the value of the DHCPv6 option  is  a
                     domain  name encoded in DNS wire format (RFC 1035), where
                     each label is preceded by its length.

                     Example. "name=fqdn", "code=39", "type=domain".

                     put_dhcpv6_opts(..., fqdn = host.example.com,...)
Connection TABLE
       Configuration for a database connection to  an  Open  vSwitch  database
       (OVSDB) client.

       This  table  primarily  configures  the  Open  vSwitch  database server
       (ovsdb-server).

       The Open vSwitch database server can initiate and maintain active  con‐
       nections  to  remote  clients.  It can also listen for database connec‐
       tions.

   Summary:
       Core Features:
         target                      string (must be unique within table)
         read_only                   boolean
         role                        string
       Client Failure Detection and Handling:
         max_backoff                 optional integer, at least 1,000
         inactivity_probe            optional integer
       Status:
         is_connected                boolean
         status : last_error         optional string
         status : state              optional string, one of ACTIVE,  BACKOFF,
                                     CONNECTING, IDLE, or VOID
         status : sec_since_connect  optional  string,  containing an integer,
                                     at least 0
         status : sec_since_disconnect
                                     optional string, containing  an  integer,
                                     at least 0
         status : locks_held         optional string
         status : locks_waiting      optional string
         status : locks_lost         optional string
         status : n_connections      optional  string,  containing an integer,
                                     at least 2
         status : bound_port         optional string, containing an integer
       Common Columns:
         external_ids                map of string-string pairs
         other_config                map of string-string pairs

   Details:
     Core Features:

       target: string (must be unique within table)
              Connection methods for clients.

              The following connection methods are currently supported:

              ssl:host[:port]
                     The specified SSL/TLS port on the given host,  which  can
                     either  be  a DNS name (if built with unbound library) or
                     an IP address. A valid SSL configuration must be provided
                     when this form is used, this configuration can be  speci‐
                     fied via command-line options or the SSL table.

                     If port is not specified, it defaults to 6640.

                     SSL/TLS support is an optional feature that is not always
                     built as part of OVN or Open vSwitch.

              tcp:host[:port]
                     The  specified  TCP port on the given host, which can ei‐
                     ther be a DNS name (if built with unbound library) or  an
                     IP  address  (IPv4  or IPv6). If host is an IPv6 address,
                     wrap it in square brackets, e.g. tcp:[::1]:6640.

                     If port is not specified, it defaults to 6640.

              pssl:[port][:host]
                     Listens for SSL/TLS  connections  on  the  specified  TCP
                     port. Specify 0 for port to have the kernel automatically
                     choose  an available port. If host, which can either be a
                     DNS name (if built with unbound library)  or  an  IP  ad‐
                     dress,  is  specified, then connections are restricted to
                     the resolved or specified local IP address  (either  IPv4
                     or  IPv6  address).  If  host is an IPv6 address, wrap in
                     square brackets, e.g. pssl:6640:[::1].  If  host  is  not
                     specified then it listens only on IPv4 (but not IPv6) ad‐
                     dresses.  A  valid SSL/TLS configuration must be provided
                     when this form is used, this can be specified either  via
                     command-line options or the SSL table.

                     If port is not specified, it defaults to 6640.

                     SSL/TLS support is an optional feature that is not always
                     built as part of OVN or Open vSwitch.

              ptcp:[port][:host]
                     Listens  for connections on the specified TCP port. Spec‐
                     ify 0 for port to have the kernel automatically choose an
                     available port. If host, which can either be a  DNS  name
                     (if  built  with  unbound  library)  or an IP address, is
                     specified, then connections are  restricted  to  the  re‐
                     solved or specified local IP address (either IPv4 or IPv6
                     address).  If  host is an IPv6 address, wrap it in square
                     brackets, e.g. ptcp:6640:[::1]. If host is not  specified
                     then it listens only on IPv4 addresses.

                     If port is not specified, it defaults to 6640.

              When  multiple clients are configured, the target values must be
              unique. Duplicate target values yield unspecified results.

       read_only: boolean
              true to restrict these connections  to  read-only  transactions,
              false to allow them to modify the database.

       role: string
              String containing role name for this connection entry.

     Client Failure Detection and Handling:

       max_backoff: optional integer, at least 1,000
              Maximum  number  of  milliseconds to wait between connection at‐
              tempts. Default is implementation-specific.

       inactivity_probe: optional integer
              Maximum number of milliseconds of idle time on connection to the
              client before sending  an  inactivity  probe  message.  If  Open
              vSwitch  does  not communicate with the client for the specified
              number of seconds, it will send a probe. If a  response  is  not
              received  for  the  same additional amount of time, Open vSwitch
              assumes the connection has been broken and  attempts  to  recon‐
              nect.  Default is implementation-specific. A value of 0 disables
              inactivity probes.

     Status:

       Key-value pair of is_connected is always updated. Other key-value pairs
       in the status columns may be updated depends on the target type.

       When target specifies a connection method that listens for inbound con‐
       nections (e.g. ptcp: or punix:), both status:n_connections and  is_con‐‐
       nected  may  also  be  updated  while the remaining key-value pairs are
       omitted.

       On the other hand, when target specifies an  outbound  connection,  all
       key-value  pairs  may  be  updated, except the above-mentioned two key-
       value pairs associated with inbound connection targets. They are  omit‐
       ted.

       is_connected: boolean
              true if currently connected to this client, false otherwise.

       status : last_error: optional string
              A human-readable description of the last error on the connection
              to  the  manager; i.e. strerror(errno). This key will exist only
              if an error has occurred.

       status : state: optional string, one of ACTIVE, BACKOFF, CONNECTING,
       IDLE, or VOID
              The state of the connection to the manager:

              VOID   Connection is disabled.

              BACKOFF
                     Attempting to reconnect at an increasing period.

              CONNECTING
                     Attempting to connect.

              ACTIVE Connected, remote host responsive.

              IDLE   Connection is idle. Waiting for response to keep-alive.

              These values may change in the future. They  are  provided  only
              for human consumption.

       status : sec_since_connect: optional string, containing an integer, at
       least 0
              The amount of time since this client last successfully connected
              to the database (in seconds). Value is empty if client has never
              successfully been connected.

       status : sec_since_disconnect: optional string, containing an integer,
       at least 0
              The  amount of time since this client last disconnected from the
              database (in seconds). Value is empty if client has  never  dis‐
              connected.

       status : locks_held: optional string
              Space-separated  list  of the names of OVSDB locks that the con‐
              nection holds. Omitted if  the  connection  does  not  hold  any
              locks.

       status : locks_waiting: optional string
              Space-separated  list  of the names of OVSDB locks that the con‐
              nection is currently waiting to acquire. Omitted if the  connec‐
              tion is not waiting for any locks.

       status : locks_lost: optional string
              Space-separated  list  of the names of OVSDB locks that the con‐
              nection has had stolen by another OVSDB client.  Omitted  if  no
              locks have been stolen from this connection.

       status : n_connections: optional string, containing an integer, at
       least 2
              When  target  specifies a connection method that listens for in‐
              bound connections (e.g. ptcp: or pssl:) and more than  one  con‐
              nection  is  actually  active, the value is the number of active
              connections. Otherwise, this key-value pair is omitted.

       status : bound_port: optional string, containing an integer
              When target is ptcp: or pssl:, this is the TCP port on which the
              OVSDB server is listening. (This  is  particularly  useful  when
              target  specifies a port of 0, allowing the kernel to choose any
              available port.)

     Common Columns:

       The overall purpose of these columns is described under Common  Columns
       at the beginning of this document.

       external_ids: map of string-string pairs

       other_config: map of string-string pairs
SSL TABLE
       SSL/TLS configuration for ovn-sb database access.

   Summary:
       private_key                   string
       certificate                   string
       ca_cert                       string
       bootstrap_ca_cert             boolean
       ssl_protocols                 string
       ssl_ciphers                   string
       ssl_ciphersuites              string
       Common Columns:
         external_ids                map of string-string pairs

   Details:
       private_key: string
              Name  of  a  PEM  file  containing  the  private key used as the
              switch’s identity for SSL/TLS connections to the controller.

       certificate: string
              Name of a PEM file containing a certificate, signed by the  cer‐
              tificate authority (CA) used by the controller and manager, that
              certifies  the  switch’s  private key, identifying a trustworthy
              switch.

       ca_cert: string
              Name of a PEM file containing the CA certificate used to  verify
              that the switch is connected to a trustworthy controller.

       bootstrap_ca_cert: boolean
              If  set to true, then Open vSwitch will attempt to obtain the CA
              certificate from the controller on its first SSL/TLS  connection
              and  save it to the named PEM file. If it is successful, it will
              immediately drop the connection and reconnect, and from then  on
              all  SSL/TLS  connections must be authenticated by a certificate
              signed by the CA certificate thus obtained. This option  exposes
              the  SSL/TLS  connection to a man-in-the-middle attack obtaining
              the initial CA certificate. It may still  be  useful  for  boot‐
              strapping.

       ssl_protocols: string
              Range  or a comma- or space-delimited list of the SSL/TLS proto‐
              cols to enable for SSL/TLS connections.

              Supported protocols include TLSv1.2 and TLSv1.3. Ranges  can  be
              provided  in  a form of two protocol names separated with a dash
              (TLSv1.2-TLSv1.3), or as a single protocol name with a plus sign
              (TLSv1.2+). The value can be a list of protocols or exactly  one
              range.  The range is a preferred way of specifying protocols and
              the configuration always behaves as if  the  range  between  the
              minimum  and the maximum specified version is provided, i.e., if
              the value is set to TLSv1.X,TLSv1.(X+2),  the  TLSv1.(X+1)  will
              also  be  enabled as if it was a range. Regardless of order, the
              highest protocol supported by both sides  will  be  chosen  when
              making the connection.

              The default when this option is omitted is TLSv1.2+.

       ssl_ciphers: string
              List  of  ciphers  (in  OpenSSL cipher string format) to be sup‐
              ported for SSL/TLS connections with TLSv1.2.  The  default  when
              this option is omitted is DEFAULT:@SECLEVEL=2.

       ssl_ciphersuites: string
              List  of ciphersuites (in OpenSSL ciphersuites string format) to
              be supported for SSL/TLS connections with TLSv1.3 and later. De‐
              fault value from OpenSSL will be used when this option is  omit‐
              ted.

     Common Columns:

       The  overall purpose of these columns is described under Common Columns
       at the beginning of this document.

       external_ids: map of string-string pairs
DNS TABLE
       Each row  in  this  table  stores  the  DNS  records.  The  OVN  action
       dns_lookup uses this table for DNS resolution.

   Summary:
       records                       map of string-string pairs
       datapaths                     set of 1 or more Datapath_Bindings
       options : ovn-owned           optional string
       Common Columns:
         external_ids                map of string-string pairs

   Details:
       records: map of string-string pairs
              Key-value pair of DNS records with DNS query name as the key and
              a  string  of  IP address(es) separated by comma or space as the
              value. ovn-northd stores the DNS query name in all lowercase  in
              order to facilitate case-insensitive lookups.

              Example:  "vm1.ovn.org" = "10.0.0.4 aef0::4"

       datapaths: set of 1 or more Datapath_Bindings
              The  DNS  records  defined in the column records will be applied
              only to the DNS queries originating from the  datapaths  defined
              in this column.

       options : ovn-owned: optional string
              This  column  indicates  that  all the Domains in this table are
              owned by OVN, and all DNS queries for those domains will be  an‐
              swered locally by either an IP address or DNS rejection.

     Common Columns:

       external_ids: map of string-string pairs
              See External IDs at the beginning of this document.

RBAC_Role TABLE
       Role table for role-based access controls.

   Summary:
       name                          string
       permissions                   map of string-weak reference to RBAC_Per‐‐
                                     mission pairs

   Details:
       name: string
              The  role  name, corresponding to the role column in the Connec‐‐
              tion table.

       permissions: map of string-weak reference to RBAC_Permission pairs
              A mapping of table names to rows in the RBAC_Permission table.

RBAC_Permission TABLE
       Permissions table for role-based access controls.

   Summary:
       table                         string
       authorization                 set of strings
       insert_delete                 boolean
       update                        set of strings

   Details:
       table: string
              Name of table to which this row applies.

       authorization: set of strings
              Set of strings identifying columns and column:key  pairs  to  be
              compared with client ID. At least one match is required in order
              to  be  authorized. A zero-length string is treated as a special
              value indicating all clients should be considered authorized.

       insert_delete: boolean
              When "true", row insertions and  authorized  row  deletions  are
              permitted.

       update: set of strings
              Set of strings identifying columns and column:key pairs that au‐
              thorized clients are allowed to modify.

Gateway_Chassis TABLE
       Association  of Port_Binding rows of type chassisredirect to a Chassis.
       The traffic going out through a specific chassisredirect port  will  be
       redirected to a chassis, or a set of them in high availability configu‐
       rations.

   Summary:
       name                          string (must be unique within table)
       chassis                       optional weak reference to Chassis
       priority                      integer, in range 0 to 32,767
       options                       map of string-string pairs
       Common Columns:
         external_ids                map of string-string pairs

   Details:
       name: string (must be unique within table)
              Name of the Gateway_Chassis.

              A   suggested,   but   not   required   naming   convention   is
              ${port_name}_${chassis_name}.

       chassis: optional weak reference to Chassis
              The Chassis to which we send the traffic.

       priority: integer, in range 0 to 32,767
              This is the  priority  the  specific  Chassis  among  all  Gate‐
              way_Chassis belonging to the same Port_Binding.

       options: map of string-string pairs
              Reserved for future use.

     Common Columns:

       The  overall purpose of these columns is described under Common Columns
       at the beginning of this document.

       external_ids: map of string-string pairs
HA_Chassis TABLE
   Summary:
       chassis                       optional weak reference to Chassis
       priority                      integer, in range 0 to 32,767
       Common Columns:
         external_ids                map of string-string pairs

   Details:
       chassis: optional weak reference to Chassis
              The Chassis which provides the HA functionality.

       priority: integer, in range 0 to 32,767
              Priority of the HA chassis. Chassis with highest  priority  will
              be the active chassis in the HA chassis group.

     Common Columns:

       external_ids: map of string-string pairs
              See External IDs at the beginning of this document.

HA_Chassis_Group TABLE
       Table representing a group of chassis which can provide High availabil‐
       ity  services.  Each  chassis  in the group is represented by the table
       HA_Chassis. The HA chassis with highest priority  will  be  the  active
       chassis  of this group. If the active chassis failover is detected, the
       HA chassis with the next higher priority takes over the  responsibility
       of providing the HA. If ha_chassis_group column of the table Port_Bind‐‐
       ing  references  this  table,  then  this HA chassis group provides the
       gateway functionality and redirects the gateway traffic to  the  active
       chassis of this group.

   Summary:
       name                          string (must be unique within table)
       ha_chassis                    set of HA_Chassises
       ref_chassis                   set of weak reference to Chassis
       Common Columns:
         external_ids                map of string-string pairs

   Details:
       name: string (must be unique within table)
              Name of the HA_Chassis_Group. Name should be unique.

       ha_chassis: set of HA_Chassises
              A list of HA_Chassis which belongs to this group.

       ref_chassis: set of weak reference to Chassis
              The  set of Chassis that reference this HA chassis group. To de‐
              termine the  correct  Chassis,  find  the  chassisredirect  type
              Port_Binding   that   references   this  HA_Chassis_Group.  This
              Port_Binding is derived from  some  particular  logical  router.
              Starting  from that LR, find the set of all logical switches and
              routers connected to it, directly or indirectly,  across  router
              ports  that link one LRP to another or to a LSP. For each LSP in
              these logical switches, find the corresponding Port_Binding  and
              add its bound Chassis (if any) to ref_chassis.

     Common Columns:

       external_ids: map of string-string pairs
              See External IDs at the beginning of this document.

Controller_Event TABLE
       Database  table  used  by  ovn-controller to report CMS related events.
       Please note there is no guarantee a given event is written exactly once
       in the db. It is CMS responsibility to squash duplicated  lines  or  to
       filter out duplicated events

   Summary:
       event_type                    string, must be empty_lb_backends
       event_info                    map of string-string pairs
       chassis                       optional weak reference to Chassis
       seq_num                       integer

   Details:
       event_type: string, must be empty_lb_backends
              Event type occurred

       event_info: map of string-string pairs
              Key-value  pairs used to specify event info to the CMS. Possible
              values are:

              •      vip: VIP reported for the empty_lb_backends event

              •      protocol:   Transport   protocol   reported    for    the
                     empty_lb_backends event

              •      load_balancer: UUID of the load balancer reported for the
                     empty_lb_backends event

       chassis: optional weak reference to Chassis
              This column is a Chassis record to identify the chassis that has
              managed a given event.

       seq_num: integer
              Event  sequence  number. Global counter for controller generated
              events. It can be used by the CMS to detect possible duplication
              of the same event.
IP_Multicast TABLE
       IP Multicast configuration options. For now only applicable to IGMP.

   Summary:
       datapath                      weak reference to Datapath_Binding  (must
                                     be unique within table)
       enabled                       optional boolean
       querier                       optional boolean
       table_size                    optional integer
       idle_timeout                  optional integer
       query_interval                optional integer
       seq_no                        integer
       Querier configuration options:
         eth_src                     string
         ip4_src                     string
         ip6_src                     string
         query_max_resp              optional integer

   Details:
       datapath: weak reference to Datapath_Binding (must be unique within ta‐
       ble)
              Datapath_Binding entry for which these configuration options are
              defined.

       enabled: optional boolean
              Enables/disables multicast snooping. Default: disabled.

       querier: optional boolean
              Enables/disables  multicast  querying. If enabled then multicast
              querying is enabled by default.

       table_size: optional integer
              Limits the number of multicast groups that can be  learned.  De‐
              fault: 2048 groups per datapath.

       idle_timeout: optional integer
              Configures the idle timeout (in seconds) for IP multicast groups
              if multicast snooping is enabled. Default: 300 seconds.

       query_interval: optional integer
              Configures  the  interval  (in  seconds)  for  sending multicast
              queries if snooping and querier are enabled. Default: idle_time‐‐
              out/2 seconds.

       seq_no: integer
              ovn-controller reads this value and flushes all  learned  multi‐
              cast groups when it detects that seq_no was changed.

     Querier configuration options:

       The  ovn-controller  process that runs on OVN hypervisor nodes uses the
       following columns to determine field values in IGMP/MLD queries that it
       originates:

       eth_src: string
              Source Ethernet address.

       ip4_src: string
              Source IPv4 address.

       ip6_src: string
              Source IPv6 address.

       query_max_resp: optional integer
              Value (in seconds) to be used as "max-response" field in  multi‐
              cast queries. Default: 1 second.

IGMP_Group TABLE
       Contains learned IGMP groups indexed by address/datapath/chassis.

   Summary:
       address                       string
       protocol                      string
       datapath                      optional weak reference to Datapath_Bind‐‐
                                     ing
       chassis                       optional weak reference to Chassis
       ports                         set of weak reference to Port_Bindings
       chassis_name                  string

   Details:
       address: string
              Destination IPv4 address for the IGMP group.

       protocol: string
              Group protocol version either IGMPv1,v2,v3 or MLDv1,v2.

       datapath: optional weak reference to Datapath_Binding
              Datapath to which this IGMP group belongs.

       chassis: optional weak reference to Chassis
              Chassis to which this IGMP group belongs.

       ports: set of weak reference to Port_Bindings
              The destination port bindings for this IGMP group.

       chassis_name: string
              The  chassis  that inserted this record. This column is used for
              RBAC purposes only.

Service_Monitor TABLE
       Each row in this table configures monitoring a service  for  its  live‐
       ness. The service can be an IPv4 TCP or UDP service. ovn-controller pe‐
       riodically  sends out service monitor packets and updates the status of
       the service. If the service monitor is not local, then ovn-ic creates a
       record about it in the SBDB database, after which another  OVN  deploy‐
       ment  creates  a  record  about the Service Monitor in its SBDB and the
       status is propagated back to the initial record in the original  avail‐
       ability zone.

       ovn-northd  uses  this  feature  to  implement the load balancer health
       check feature offered to the CMS through the northbound database.

   Summary:
       Configuration:
         type                        optional string,  one  of  load-balancer,
                                     logical-switch-port, or network-function
         ip                          string
         mac                         string
         protocol                    optional string, one of icmp, tcp, or udp
         port                        integer, in range 0 to 65,535
         logical_input_port          string
         logical_port                string
         src_mac                     string
         src_ip                      string
         chassis_name                string
         remote                      boolean
         ic_learned                  boolean
         options : interval          optional string, containing an integer
         options : timeout           optional string, containing an integer
         options : success_count     optional string, containing an integer
         options : failure_count     optional string, containing an integer
       Status Reporting:
         status                      optional  string,  one of error, offline,
                                     or online
       Common Columns:
         external_ids                map of string-string pairs

   Details:
     Configuration:

       ovn-northd sets these columns and values to configure the service moni‐
       tor.

       type: optional string, one of load-balancer, logical-switch-port, or
       network-function
              The type of the service. Supported values  are  "load-balancer",
              "network-function", and "logical-switch-port".

       ip: string
              Destination  IP  used in monitor packets. For load-balancer ser‐
              vice this is the IP of the service to be monitored. For network-
              function service this IP is used to send probe  packets  through
              the associated Network Function port pair.

       mac: string
              Destination MAC address used in monitor packets. This is applic‐
              able only for network-function services.

       protocol: optional string, one of icmp, tcp, or udp
              The  protocol  of the service. For type load-balancer, supported
              protocols are tcp and udp.  For  type  "network-function",  sup‐
              ported protocol is icmp, and the health probe is done by inject‐
              ing  an  icmp  echo  request  packet into the inport of the Net‐
              work_Function and then monitoring the same packet coming out  of
              the outport. For type "logical-switch-port", supported protocols
              are tcp, udp and icmp.

       port: integer, in range 0 to 65,535
              The TCP or UDP port of the service.

       logical_input_port: string
              This  is  applicable  only for network-function type. The VIF of
              the logical port on which monitor packets have to be  sent.  The
              ovn-controller that binds this logical_port monitors the service
              by sending periodic monitor packets.

       logical_port: string
              The VIF of the logical port on which the service is running. The
              ovn-controller that binds this logical_port monitors the service
              by  sending  periodic monitor packets. For load-balancer this is
              the port to which monitor packets are sent and  from  which  re‐
              sponse  packets  are  received. For network-function this is the
              port from which the forwarded monitor packets are received.

       src_mac: string
              Source Ethernet address to use in the service monitor packet.

       src_ip: string
              Source IPv4 or IPv6  address  to  use  in  the  service  monitor
              packet.

       chassis_name: string
              The name of the chassis where the logical port is bound.

       remote: boolean
              Set to true if backend is located on a remote ovn deployment.

       ic_learned: boolean
              Set  to  true if the service monitor was propagated from another
              OVN deployment via ovn-ic management.

       options : interval: optional string, containing an integer
              The interval, in seconds, between service monitor checks.

       options : timeout: optional string, containing an integer
              The time, in seconds, after  which  the  service  monitor  check
              times out.

       options : success_count: optional string, containing an integer
              The  number of successful checks after which the service is con‐
              sidered online.

       options : failure_count: optional string, containing an integer
              The number of failure checks after which the service is  consid‐
              ered offline.

     Status Reporting:

       The  ovn-controller  on the chassis that hosts the logical_port updates
       this column to report the service’s status.

       status: optional string, one of error, offline, or online
              For TCP service, ovn-controller sends a SYN to the  service  and
              expects an ACK response to consider the service to be online.

              For  UDP  service, ovn-controller sends a UDP packet to the ser‐
              vice and doesn’t expect any reply. If it receives an ICMP reply,
              then it considers the service to be offline.

              For ICMP service, ovn-controller sends an ICMP Echo Request  and
              expects  an ICMP Echo Reply to consider service to be online. If
              no reply is received or if an ICMP error  message  is  received,
              the service is considered offline.

              The  value  error  is  also  valid  but  is not currently set by
              ovn-controller.

     Common Columns:

       external_ids: map of string-string pairs
              See External IDs at the beginning of this document.

Load_Balancer TABLE
       Each row represents a load balancer.

   Summary:
       name                          string
       vips                          map of string-string pairs
       protocol                      optional string, one of sctp, tcp, or udp
       datapaths                     set of Datapath_Bindings
       datapath_group                optional Logical_DP_Group
       ls_datapath_group             optional Logical_DP_Group
       lr_datapath_group             optional Logical_DP_Group
       Load_Balancer options:
         options : hairpin_snat_ip   optional string
       Common Columns:
         external_ids                map of string-string pairs

   Details:
       name: string
              A name for the load balancer. This name has no  special  meaning
              or  purpose other than to provide convenience for human interac‐
              tion with the ovn-sb database.

       vips: map of string-string pairs
              A map of virtual IP addresses (and an optional port number  with
              :  as  a separator) associated with this load balancer and their
              corresponding endpoint IP addresses (and optional  port  numbers
              with : as separators) separated by commas.

       protocol: optional string, one of sctp, tcp, or udp
              Valid  protocols  are  tcp,  udp, or sctp. This column is useful
              when a port number is provided as part of the  vips  column.  If
              this  column  is  empty and a port number is provided as part of
              vips column, OVN assumes the protocol to be tcp.

       datapaths: set of Datapath_Bindings
              Datapaths to which this load balancer applies to.

       datapath_group: optional Logical_DP_Group
              Deprecated. The group of datapaths to which this  load  balancer
              applies  to.  This  means that the same load balancer applies to
              all datapaths in a group.

       ls_datapath_group: optional Logical_DP_Group
              The group of datapaths to which this load balancer  applies  to.
              This  means that the same load balancer applies to all datapaths
              in a group.

       lr_datapath_group: optional Logical_DP_Group
              The group of logical router datapaths to which  this  load  bal‐
              ancer applies to. This means that the same load balancer applies
              to all datapaths in a group.

     Load_Balancer options:

       options : hairpin_snat_ip: optional string
              IP  to  be  used  as  source IP for packets that have been hair-
              pinned after load balancing. This value is  automatically  popu‐
              lated by ovn-northd.

     Common Columns:

       external_ids: map of string-string pairs
              See External IDs at the beginning of this document.

BFD TABLE
       Contains BFD parameter for ovn-controller bfd configuration.

   Summary:
       Configuration:
         src_port                    integer, in range 49,152 to 65,535
         disc                        integer
         logical_port                string
         dst_ip                      string
         min_tx                      integer
         min_rx                      integer
         detect_mult                 integer
         chassis_name                string
         options                     map of string-string pairs
         external_ids                map of string-string pairs
       Status Reporting:
         status                      string, one of admin_down, down, init, or
                                     up

   Details:
     Configuration:

       src_port: integer, in range 49,152 to 65,535
              udp  source  port  used  in bfd control packets. The source port
              MUST be in the range 49152 through 65535 (RFC5881 section 4).

       disc: integer
              A unique, nonzero discriminator value generated by the transmit‐
              ting system, used to demultiplex multiple BFD  sessions  between
              the same pair of systems.

       logical_port: string
              OVN logical port when BFD engine is running.

       dst_ip: string
              BFD peer IP address.

       min_tx: integer
              This  is  the  minimum interval, in milliseconds, that the local
              system would like to use when transmitting BFD Control  packets,
              less any jitter applied. The value zero is reserved.

       min_rx: integer
              This  is the minimum interval, in milliseconds, between received
              BFD Control packets that this system is capable  of  supporting,
              less  any  jitter  applied by the sender. If this value is zero,
              the transmitting system does not want the remote system to  send
              any periodic BFD Control packets.

       detect_mult: integer
              Detection  time  multiplier.  The  negotiated transmit interval,
              multiplied by this value, provides the Detection  Time  for  the
              receiving system in Asynchronous mode.

       chassis_name: string
              The name of the chassis where the logical port is bound.

       options: map of string-string pairs
              Reserved for future use.

       external_ids: map of string-string pairs
              See External IDs at the beginning of this document.

     Status Reporting:

       status: string, one of admin_down, down, init, or up
              BFD port logical states. Possible values are:

              •      admin_downdowninitup
FDB TABLE
       This  table is primarily used to learn the MACs observed on a VIF (or a
       localnet port with ’localnet_learn_fdb’ enabled)  which  belongs  to  a
       Logical_Switch_Port  record  in  OVN_Northbound  whose port security is
       disabled and ’unknown’ address set. If port security is disabled  on  a
       Logical_Switch_Port  record,  OVN  should allow traffic with any source
       mac from the VIF. This table will be used to deliver a  packet  to  the
       VIF, if a packet’s eth.dst is learnt.

   Summary:
       mac                           string
       dp_key                        integer, in range 1 to 16,777,215
       port_key                      integer, in range 1 to 16,777,215
       timestamp                     integer

   Details:
       mac: string
              The learnt mac address.

       dp_key: integer, in range 1 to 16,777,215
              The key of the datapath on which this FDB was learnt.

       port_key: integer, in range 1 to 16,777,215
              The key of the port binding on which this FDB was learnt.

       timestamp: integer
              The timestamp in msec when the FDB was added or updated. Records
              that existed before this column will have 0.

Static_MAC_Binding TABLE
       Each record represents a Static_MAC_Binding entry for a logical router.

   Summary:
       logical_port                  string
       ip                            string
       mac                           string
       override_dynamic_mac          boolean
       datapath                      Datapath_Binding

   Details:
       logical_port: string
              The logical router port for the binding.

       ip: string
              The bound IP address.

       mac: string
              The Ethernet address to which the IP is bound.

       override_dynamic_mac: boolean
              Override dynamically learnt MACs.

       datapath: Datapath_Binding
              The logical datapath to which the logical router port belongs.

Chassis_Template_Var TABLE
       Each  record represents the set of template variable instantiations for
       a given chassis and is populated by ovn-northd from the contents of the
       OVN_Northbound.Chassis_Template_Var table.

   Summary:
       chassis                       string (must be unique within table)
       variables                     map of string-string pairs

   Details:
       chassis: string (must be unique within table)
              The chassis this set of variable values applies to.

       variables: map of string-string pairs
              The set of variable values for a given chassis.

Advertised_Route TABLE
       Each record represents a route that should be exported from ovn to  the
       outside  network fabric. It is populated by ovn-northd based on the ad‐
       dresses,   routes   and   NAT   Entries   of   a   OVN_Northbound.Logi‐‐
       cal_Router_Port.

   Summary:
       datapath                      Datapath_Binding
       logical_port                  Port_Binding
       ip_prefix                     string
       tracked_port                  optional Port_Binding
       external_ids                  map of string-string pairs

   Details:
       datapath: Datapath_Binding
              The datapath belonging to the OVN_Northbound.Logical_Router that
              this route is valid for.

       logical_port: Port_Binding
              This  is  the Port_Binding that the router will send packets out
              that are received for the below prefix.

       ip_prefix: string
              IP prefix of this route (e.g. 192.168.100.0/24).

       tracked_port: optional Port_Binding
              In combination with a host ip_prefix this tracks  the  port  OVN
              will  forward  the  packets  for this destination to. If set the
              ip_prefix will always contain a /32  (for  ipv4)  or  /128  (for
              ipv6)  prefix. An announcing chassis can use this information to
              check if this destination is local and adjust the route  priori‐
              ties based on that.

       external_ids: map of string-string pairs
              See External IDs at the beginning of this document.

              The following keys control distributed Load_Balancer routes:

              source ovn-northd  sets  this  to  lb  on  routes  derived  from
                     Load_Balancer VIPs. It is absent  on  other  routes.  The
                     controller applies LB-specific handling when this key and
                     distributed-lb=true are both present.

              distributed-lb
                     Set  to  true  by  ovn-northd when the route belongs to a
                     Load Balancer whose  options:distributed  option  is  en‐
                     abled.  The  health  gate, administrative enable flag and
                     status table apply only to routes carrying this key.

              health-checks
                     For a  health-checked  distributed  Load_Balancer  route,
                     ovn-northd   records  each  relevant  backend  as  proto‐‐
                     col,IP,port. When more than one backend is  relevant  the
                     tuples  are separated by semicolons. ovn-controller looks
                     up matching Service_Monitor rows.  When  a  shared  route
                     (same  VIP IP and backend LSP) has at least one contribu‐
                     tor without a health check, the key is absent so the con‐
                     troller does not gate the route.

              enabled
                     Administrative enable flag for routes  carrying  distrib‐‐
                     uted-lb=true.  A  value  of false withdraws the route re‐
                     gardless of Service_Monitor  health.  An  absent  key  is
                     treated  as  enabled.  A privileged administrative writer
                     can use this key to withdraw a route.
Learned_Route TABLE
       Each record represents a route that was learned by ovn using  some  dy‐
       namic  routing  logic outside of ovn. It is populated by ovn-controller
       with routes it learns locally.

   Summary:
       datapath                      Datapath_Binding
       logical_port                  Port_Binding
       ip_prefix                     string
       nexthop                       string
       external_ids                  map of string-string pairs

   Details:
       datapath: Datapath_Binding
              The datapath belonging to the OVN_Northbound.Logical_Router that
              this route is valid for.

       logical_port: Port_Binding
              This is the Port_Binding that the route was learned on.

       ip_prefix: string
              IP prefix of this route (e.g. 192.168.100.0/24).

       nexthop: string
              This is the nexthop ip we learned from outside of OVN.

       external_ids: map of string-string pairs
              See External IDs at the beginning of this document.

ECMP_Nexthop TABLE
       Each record in this table represents an active next-hop for ECMP routes
       created  with  --ecmp-symmetric-reply  option  that  are  committed  by
       ovn-northd to ovs connection tracker. The ECMP_Nexthop table is used by
       ovn-controller to track active ct entries and to flush stale ones.

   Summary:
       nexthop                       string
       port                          Port_Binding
       datapath                      Datapath_Binding
       mac                           string
       external_ids                  map of string-string pairs

   Details:
       nexthop: string
              Nexthop  IP  address  for  this  ECMP  route. Nexthop IP address
              should be the IP address of a connected router port  or  the  IP
              address of an external device used as nexthop for the given des‐
              tination.

       port: Port_Binding
              The reference to Port_Binding table for the port used to connect
              to the configured next-hop.

       datapath: Datapath_Binding
              The  reference  to Datapath_Binding table for the datapath where
              the port used to connect to the configured next-hop is running.

       mac: string
              Nexthop mac address.

       external_ids: map of string-string pairs
              See External IDs at the beginning of this document.

ACL_ID TABLE
       Each record represents an identifier that ovn-northd needs to  synchro‐
       nize  with  instances of ovn-controller. The UUID of each record corre‐
       sponds directly with an ACL record in the northbound database.

   Summary:
       id                            integer, in range 0 to 32,767

   Details:
       id: integer, in range 0 to 32,767
              An identifier corresponding to  a  northbound  allow-established
              ACL.

Advertised_MAC_Binding TABLE
       Each  record  represents  an  ip/mac  binding  the OVN_Northbound.Logi‐‐
       cal_Switch is announcing outside the network fabric if EVPN is  enabled
       on the datapath.

   Summary:
       datapath                      Datapath_Binding
       logical_port                  Port_Binding
       ip                            string
       mac                           string
       external_ids                  map of string-string pairs

   Details:
       datapath: Datapath_Binding
              The  datapath corresponding to the OVN_Northbound.Logical_Switch
              this ip/mac binding belongs to.

       logical_port: Port_Binding
              This is the Port_Binding this ip/mac binding belongs to.

       ip: string
              Announced IP (e.g. 192.168.100.1).

       mac: string
              Announced mac address.

       external_ids: map of string-string pairs
              See External IDs at the beginning of this document.

Open vSwitch 26.09.90          DB Schema 21.13.0                     ovn-sb(5)