ovn-sb man page

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 abstraction. 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 participates.

The logical network data is ultimately controlled by the cloud management 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 configuration, 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_Group, DHCP_Options, DHCPv6_Options, and DNS tables contain logical network data.

Logical-physical bindings

These tables link logical and physical components. They show the current placement of logical components (such as VMs and VIFs) onto chassis, and map logical entities to the values that represent them in tunnel 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 location, 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 networks.

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 describe 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-controller/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 comprehensive.

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

Encap

Encapsulation Types

Address_Set

Address Sets

Logical_Flow

Logical Network Flows

Multicast_Group

Logical Port Multicast Groups

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.

SB_Global TABLE

Southbound configuration for an OVN system. This table must have exactly one row.

Summary

Status:
nb_cfg

integer

Common Columns:
external_ids

map of string-string pairs

Connection Options:
connections

set of Connections

ssl

optional SSL

Details

Status:

This column allow 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.

Common Columns:

external_ids: map of string-string pairs

See External IDs at the beginning of this document.

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 Connection table for more information.

ssl: optional SSL

Global SSL configuration.

Chassis TABLE

Each row in this table represents a hypervisor or gateway (a chassis) in the physical network. Each chassis, via ovn-controller/ovn-controller-vtep, adds and updates its own row, and keeps a copy of the remaining 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

external_ids : ovn-bridge-mappings

optional string

external_ids : datapath-type

optional string

external_ids : iface-types

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-controller-vtep populates this column with name in the hardware_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

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

external_ids : ovn-bridge-mappings: optional string

ovn-controller populates this key with the set of bridge mappings it has been configured to use. Other applications should treat this key as read-only. See ovn-controller(8) for more information.

external_ids : datapath-type: optional string

ovn-controller populates this key with the datapath type configured 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.

external_ids : iface-types: optional string

ovn-controller populates this key with the interface types configured 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.

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 dedicated nodes that do not host VMs and will be controlled by ovn-controller-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-physical-switch equal Chassis name, and options:vtep-logical-switch value in Chassis vtep_logical_switches, will be associated with this Chassis.

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 chassis. 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, one of geneve, stt, or vxlan

options

map of string-string pairs

ip

string

chassis_name

string

Details

type: string, one of geneve, stt, or vxlan

The encapsulation to use to transmit packets to this chassis. Hypervisors must use either geneve or stt. Gateways may use vxlan, geneve, or stt.

options: map of string-string pairs

Options for configuring the encapsulation. Currently, the only option that has been defined is csum.

csum indicates that encapsulation checksums can be transmitted and received with reasonable performance. It is a hint 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, this actually significantly increases throughput in most common cases when running on Linux based hosts without NICs supporting encapsulation hardware offload (around 60% for bulk traffic). The reason is that generally 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 validated outer checksum can be used to additionally validate an inner 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 entire packets in their switching engines and are therefore unable to efficiently compute or validate full packet checksums. In addition certain versions of the Linux kernel are not able to fully take advantage of encapsulation NIC offloads in the presence 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.

ip: string

The IPv4 address of the encapsulation tunnel endpoint.

chassis_name: string

The name of the chassis that created this encap.

Address_Set TABLE

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

Summary

name

string (must be unique within table)

addresses

set of strings

Details

name: string (must be unique within table)

addresses: set of strings

Logical_Flow TABLE

Each row in this table represents one logical flow. ovn-northd populates 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 instead 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 centralized 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 implementation. 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 destination. 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, 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 specified. 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 logical 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 registers aren’t preserve across tunnel encapsulation).

To execute the egress pipeline, OVN again searches the Logical_Flow table for a row with correct logical_datapath, 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, except 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 description 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 described in detail in ovn-northd(8).

Summary

logical_datapath

Datapath_Binding

pipeline

string, either egress or ingress

table_id

integer, in range 0 to 23

priority

integer, in range 0 to 65,535

match

string

actions

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: Datapath_Binding

The logical datapath to which the logical flow belongs.

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 Logical Life Cycle of a Packet, above, for details.

table_id: integer, in range 0 to 23

The stage in the logical pipeline, analogous to an OpenFlow table 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 expressions in a programming language.

The most important components of match expression are comparisons 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 itself 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 Measurement, below).

  • Subfields. A subfield represents a subset of bits from a larger field. For example, a field vlan.vid might be defined as an alias for vlan.tci[0..11]. Subfields are provided 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 expression. Predicates may be used much like 1-bit fields. For example, ip4 might expand to eth.type == 0x800. Predicates are provided for syntactic convenience, because it is always possible to instead specify the underlying expression directly.

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

Level of Measurement. See http://en.wikipedia.org/wiki/Level_of_measurement for the statistical 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 ordinal if its bits can be examined individually. This is true for the OpenFlow fields that OpenFlow or Open vSwitch makes ``maskable.’’

    Any use of a nominal 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 (==, !=, <, <=, >, and >=) 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. This is true of OpenFlow port numbers, Ethernet 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 nominal 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 priority.)

    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: either one can be implemented as a test for 0 or 1.

    Only predicates (see above) have a Boolean level of measurement.

    This isn’t a standard level of measurement.

Prerequisites. Any symbol can have prerequisites, which are additional condition implied by the use of the symbol. For example, For example, 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 ==, !=, <, <=, >, and >= 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 efficient than that of the other relational operators.

Constants

Integer constants may be expressed in decimal, hexadecimal prefixed 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 integers, 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.

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 symobl == 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 implementation 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 required.

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 || require 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.

  • ()
  • ==   !=   <   <=   >   >=
  • !
  • &&   ||

Comments may be introduced by //, which extends to the next new-line. Comments within a line may be bracketed by /* and */. Multiline 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. outport 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-signficant. xxreg1 similarly overlays reg4 through reg7.

  • reg0...reg9
  • xxreg0 xxreg1
  • inport outport
  • flags.loopback
  • eth.src eth.dst eth.type
  • vlan.tci vlan.vid vlan.pcp vlan.present
  • ip.proto ip.dscp ip.ecn ip.ttl ip.frag
  • ip4.src ip4.dst
  • ip6.src ip6.dst ip6.label
  • arp.op arp.spa arp.tpa arp.sha arp.tha
  • tcp.src tcp.dst tcp.flags
  • udp.src udp.dst
  • sctp.src sctp.dst
  • icmp4.type icmp4.code
  • icmp6.type icmp6.code
  • nd.target nd.sll nd.tll
  • ct_mark ct_label
  • ct_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 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:ff
  • eth.mcast expands to eth.dst[40]
  • vlan.present expands to vlan.tci[12]
  • ip4 expands to eth.type == 0x800
  • ip4.mcast expands to ip4.dst[28..31] == 0xe
  • ip6 expands to eth.type == 0x86dd
  • ip expands to ip4 || ip6
  • icmp4 expands to ip4 && ip.proto == 1
  • icmp6 expands to ip6 && ip.proto == 58
  • icmp expands to icmp4 || icmp6
  • ip.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_frag
  • arp expands to eth.type == 0x806
  • nd expands to icmp6.type == {135, 136} && icmp6.code == 0 && ip.ttl == 255
  • nd_ns expands to icmp6.type == 135 && icmp6.code == 0 && ip.ttl == 255
  • nd_na expands to icmp6.type == 136 && icmp6.code == 0 && ip.ttl == 255
  • tcp expands to ip.proto == 6
  • udp expands to ip.proto == 17
  • sctp 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 contain 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 multicast group, the egress pipeline runs once for each logical 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. Actions in the ingress pipeline may not use next to jump into the egress pipeline (use the output instead), but transitions in the opposite direction are allowed.

field = constant;

Sets data or metadata field field to constant value constant, 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 sigificant 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 partially modified (e.g. ip.ttl must assigned as a whole). The outport field is modifiable in the ingress pipeline but not in the egress pipeline.

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, specify 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 implicitly 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 <-> field2;

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

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 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. 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 is 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 supplied, 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.

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_dnat;
ct_dnat(IP);

ct_dnat sends the packet through the DNAT zone in connection tracking table to unDNAT any packet that was DNATed in the opposite direction. The packet is then automatically sent to 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 behavior on gateway routers differs from the behavior on a distributed router:

  • On a gateway router, if the packet needs to be sent to the next tables, then it should be followed by a next; action. The next tables will not see the changes in the packet caused by the connection tracker.
  • On a distributed router, if the connection tracker finds a connection that was SNATed in the opposite direction, then the destination IP address of the packet is UNSNATed. The packet is automatically sent to the next tables as if followed 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 provided inside the parenthesis 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.

clone { action; ... };

Makes a copy of the packet being processed and executes each action on the copy. Actions following the clone action, 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 = 0x0806
  • arp.op = 1 (ARP request)
  • arp.sha copied from eth.src
  • arp.spa copied from ip4.src
  • arp.tha = 00:00:00:00:00:00
  • arp.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);

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.src
  • eth.type = 0x86dd
  • ip6.dst copied from ip6.src
  • ip6.src copied from nd.target
  • icmp6.type = 136 (Neighbor Advertisement)
  • nd.target unchanged
  • nd.sll = 00:00:00:00:00:00
  • nd.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 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_nd(outport, ip6.dst);

put_nd(P, A, E);

Parameters: logical port string field P, 128-bit IPv6 address 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 = 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_Option table control the DHCP option 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 options 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 unchanged 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 action. 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;
ct_lb(ip[:port]...);

With one or more arguments, ct_lb commits the packet to the connection tracking table and DNATs the packet’s destination IP address (and port) to the IP address or addresses (and optional ports) specified in the string. If multiple comma-separated IP addresses are specified, each is given equal weight for picking the DNAT address. 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.

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

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 resolve 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 request 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

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 ovs-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 currently 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.

The following actions will likely be useful later, but they have not been thought out carefully.

icmp4 { action; ... };

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

The ICMPv4 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. Ethernet and IPv4 fields not listed here are not changed:

  • ip.proto = 1 (ICMPv4)
  • ip.frag = 0 (not a fragment)
  • icmp4.type = 3 (destination unreachable)
  • icmp4.code = 1 (host unreachable)

Details TBD.

Prerequisite: ip4

tcp_reset;

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.

Details TBD.

Prerequisite: tcp

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 a OVN_Northbound record that caused this logical flow to be created. Currently used only for attribute of logical flows to northbound ACL records.

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

Multicast_Group TABLE

The rows in this table define multicast groups of logical ports. Multicast groups allow a single packet transmitted over a tunnel to a hypervisor 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 tunnel_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 1 or more 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 1 or more 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).

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 implements either a logical switch or a logical router.

The main purpose of a row in this table is provide a physical binding for a logical datapath. A logical datapath does not have a physical location, so its physical binding information is limited: just tunnel_key. The rest of the data in this table does not affect packet forwarding.

Summary

tunnel_key

integer, in range 1 to 16,777,215 (must be unique within table)

OVN_Northbound Relationship:
external_ids : logical-switch

optional string, containing an uuid

external_ids : logical-router

optional string, containing an uuid

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 encapsulation.

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 datapath with concepts in the OVN_Northbound database.

external_ids : logical-switch: optional string, containing an uuid

For a logical datapath that represents a logical switch, ovn-northd stores in this key the UUID of the corresponding Logical_Switch row in the OVN_Northbound database.

external_ids : logical-router: optional string, containing an uuid

For a logical datapath that represents a logical router, ovn-northd stores in this key the UUID of the corresponding Logical_Router 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 example 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 column, 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 hypervisor/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 IntegrationGuide.rst. (The exceptions are for Port_Binding records with type of l3gateway, whose locations are identified by ovn-northd via the options:l3gateway-chassis column in this table. ovn-controller is still responsible to populate the chassis column.)

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)

chassis

optional weak reference to Chassis

gateway_chassis

set of Gateway_Chassiss

tunnel_key

integer, in range 1 to 32,767

mac

set of strings

type

string

Patch Options:
options : peer

optional string

nat_addresses

set of strings

L3 Gateway Options:
options : peer

optional string

options : l3gateway-chassis

optional string

options : nat-addresses

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 : qos_max_rate

optional string

options : qos_burst

optional string

options : qdisc_queue_id

optional string, containing an integer, in range 1 to 61,440

Chassis Redirect Options:
options : distributed-port

optional string

options : redirect-chassis

optional string

Nested Containers:
parent_port

optional string

tag

optional integer, in range 1 to 4,095

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, taken from name in the OVN_Northbound database’s Logical_Switch_Port table. OVN does not prescribe a particular format for the logical port ID.

chassis: optional weak reference to Chassis

The meaning of this column depends on the value of the type column. This is the meaning for each type

(empty string)

The physical location of the logical port. To successfully 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 chassis that has connectivity to the corresponding physical network.

localport

Always empty. A localport port is present on every chassis.

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.

gateway_chassis: set of Gateway_Chassiss

A list of Gateway_Chassis.

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

tunnel_key: integer, in range 1 to 32,767

A number that represents the logical port in the key (e.g. STT key or Geneve TLV) field carried within tunnel protocol packets.

The tunnel ID must be unique within the scope of a logical datapath.

mac: set of strings

The Ethernet address or addresses used as a source address on the logical port, each in the form xx:xx:xx:xx:xx:xx. The string unknown is also allowed to indicate that the logical port has an unknown set of (additional) source addresses.

A VM interface would ordinarily have a single Ethernet address. A gateway port might initially only have unknown, and then add MAC addresses to the set as it learns new source addresses.

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 following 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 datapaths, 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 connecting a logical switch with a Gateway router (which is only resident on a particular chassis).

localnet

A connection to a locally accessible network from each ovn-controller instance. A logical switch can only have a single localnet port attached. This is used to model direct connectivity to an existing network.

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 options: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 logical 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.

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 logical_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 addresses, followed by is_chassis_resident("lport"), where lport is the name of a logical port on the same chassis where the corresponding NAT rules are applied. This is used to send gratuitous 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.

options : nat-addresses: optional string

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 versions prior to 2.8.

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 chassis 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.

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 incoming 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 during 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.

options : qos_max_rate: optional string

If set, indicates the maximum rate for data sent from this interface, 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 : 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.

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-chassis: optional string

The chassis that this chassisredirect port is bound to. This is taken from options:redirect-chassis in the OVN_Northbound database’s Logical_Router_Port table.

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 localnet (see Localnet Options, above) or l2gateway (see L2 Gateway Options, above).

Naming:

external_ids : name: optional string

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

For a logical switch 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 table 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(logical_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 generates 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 deliver it only to ports that have no static IP-to-MAC bindings, but this could also be surprising behavior.)

4.

A host or VM on hypervisor 2 (which might be the same as hypervisor 1) attached to the logical switch owns the IP address 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 directly to the bound Ethernet address.

Summary

logical_port

string

ip

string

mac

string

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.

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, 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, 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".

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 defined here.

Summary

name

string

code

integer, in range 0 to 254

type

string, one of 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 appropriate RFC.

Example. code=3

type: string, one of 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 = 01:02:03:04L05:06,...)

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 connections to remote clients. It can also listen for database connections.

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:ip[:port]

The specified SSL port on the host at the given ip, which must be expressed as an IP address (not a DNS name). A valid SSL configuration must be provided when this form is used, this configuration can be specified via command-line options or the SSL table.

If port is not specified, it defaults to 6640.

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

tcp:ip[:port]

The specified TCP port on the host at the given ip, which must be expressed as an IP address (not a DNS name), where ip can be IPv4 or IPv6 address. If ip 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][:ip]

Listens for SSL connections on the specified TCP port. Specify 0 for port to have the kernel automatically choose an available port. If ip, which must be expressed as an IP address (not a DNS name), is specified, then connections are restricted to the specified local IP address (either IPv4 or IPv6 address). If ip is an IPv6 address, wrap in square brackets, e.g. pssl:6640:[::1]. If ip is not specified then it listens only on IPv4 (but not IPv6) addresses. A valid SSL 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 support is an optional feature that is not always built as part of Open vSwitch.

ptcp:[port][:ip]

Listens for connections on the specified TCP port. Specify 0 for port to have the kernel automatically choose an available port. If ip, which must be expressed as an IP address (not a DNS name), is specified, then connections are restricted to the specified local IP address (either IPv4 or IPv6 address). If ip is an IPv6 address, wrap it in square brackets, e.g. ptcp:6640:[::1]. If ip 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 attempts. 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 reconnect. 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 connections (e.g. ptcp: or punix:), both n_connections and is_connected 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 omitted.

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 disconnected.

status : locks_held: optional string

Space-separated list of the names of OVSDB locks that the connection 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 connection is currently waiting to acquire. Omitted if the connection is not waiting for any locks.

status : locks_lost: optional string

Space-separated list of the names of OVSDB locks that the connection 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 inbound connections (e.g. ptcp: or pssl:) and more than one connection 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 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

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 connections to the controller.

certificate: string

Name of a PEM file containing a certificate, signed by the certificate 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 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 connections must be authenticated by a certificate signed by the CA certificate thus obtained. This option exposes the SSL connection to a man-in-the-middle attack obtaining the initial CA certificate. It may still be useful for bootstrapping.

ssl_protocols: string

List of SSL protocols to be enabled for SSL connections. The default when this option is omitted is TLSv1,TLSv1.1,TLSv1.2.

ssl_ciphers: string

List of ciphers (in OpenSSL cipher string format) to be supported for SSL connections. The default when this option is omitted is HIGH:!aNULL:!MD5.

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

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.

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.

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_Permission pairs

Details

name: string

The role name, corresponding to the role column in the Connection 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 authorized 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 configurations.

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 Gateway_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

Referenced By

ovn-architecture(7), ovn-controller(8), ovn-controller-vtep(8), ovn-northd(8), ovn-sbctl(8), ovn-trace(8).

DB Schema 1.15.0 Open vSwitch 2.8.1 Open vSwitch Manual