This database is the interface between OVN and the cloud management system (CMS), such as OpenStack, running above it. The CMS produces almost all of the contents of the database. The ovn-northd program monitors the database contents, transforms it, and stores it into the database.

We generally speak of ``the'' CMS, but one can imagine scenarios in which multiple CMSes manage different parts of an OVN deployment.

External IDs

Each of the tables in this database contains a special column, named external_ids. This column has the same form and purpose each place it appears.

external_ids: map of string-string pairs: Key-value pairs for use by the CMS. The CMS might use certain pairs, for example, to identify entities in its own configuration that correspond to those in this database.

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

These columns allow a client to track the overall configuration state of the system. Sequence number for client to increment. When a client modifies any part of the northbound database configuration and wishes to wait for ovn-northd and possibly all of the hypervisors to finish applying the changes, it may increment this sequence number. Sequence number that ovn-northd sets to the value of after it finishes applying the corresponding configuration changes to the database. Sequence number that ovn-northd sets to the smallest sequence number of all the chassis in the system, as reported in the Chassis table in the southbound database. Thus, equals if all chassis are caught up with the northbound configuration (which may never happen, if any chassis is down). This value can regress, if a chassis was removed from the system and rejoins before catching up. See External IDs at the beginning of this document. This column provides general key/value settings. The supported options are described individually below.

These options apply when ovn-controller configures BFD on tunnels interfaces.

BFD option min-rx value to use when configuring BFD on tunnel interfaces. BFD option decay-min-rx value to use when configuring BFD on tunnel interfaces. BFD option min-tx value to use when configuring BFD on tunnel interfaces. BFD option mult value to use when configuring BFD on tunnel interfaces. Configure a given OUI to be used as prefix when L2 address is dynamically assigned, e.g. 00:11:22 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 table for more information. Global SSL configuration. Tunnel encryption configuration. If this column is set to be true, all OVN tunnels will be encrypted with IPsec.

Each row represents one L2 logical switch.

There are two kinds of logical switches, that is, ones that fully virtualize the network (overlay logical switches) and ones that provide simple connectivity to a physical network (bridged logical switches). They work in the same way when providing connectivity between logical ports on same chasis, but differently when connecting remote logical ports. Overlay logical switches connect remote logical ports by tunnels, while bridged logical switches provide connectivity to remote ports by bridging the packets to directly connected physical L2 segment with the help of localnet ports. Each bridged logical switch has one and only one localnet port, which has only one special address unknown.

The logical ports connected to the logical switch.

It is an error for multiple logical switches to include the same logical port.

Load balance a virtual ip address to a set of logical port endpoint ip addresses. Access control rules that apply to packets within the logical switch. QoS marking and metering rules that apply to packets within the logical switch. This column defines the DNS records to be used for resolving internal DNS queries within the logical switch by the native DNS resolver. Please see the table.

These columns provide names for the logical switch. From OVN's perspective, these names have no special meaning or purpose other than to provide convenience for human interaction with the database. There is no requirement for the name to be unique. (For a unique identifier for a logical switch, use its row UUID.)

(Originally, was intended to serve the purpose of a human-friendly name, but the Neutron integration used it to uniquely identify its own switch object, in the format neutron-uuid. Later on, Neutron started propagating the friendly name of a switch as . Perhaps this can be cleaned up someday.)

A name for the logical switch. Another name for the logical switch.

These options control automatic IP address management (IPAM) for ports attached to the logical switch. To enable IPAM for IPv4, set and optionally . To enable IPAM for IPv6, set . IPv4 and IPv6 may be enabled together or separately.

To request dynamic address assignment for a particular port, use the dynamic keyword in the column of the port's row. This requests both an IPv4 and an IPv6 address, if IPAM for IPv4 and IPv6 are both enabled.

Set this to an IPv4 subnet, e.g. 192.168.0.0/24, to enable ovn-northd to automatically assign IP addresses within that subnet.

To exclude some addresses from automatic IP address management, set this to a list of the IPv4 addresses or ..-delimited ranges to exclude. The addresses or ranges should be a subset of those in .

Whether listed or not, ovn-northd will never allocate the first or last address in a subnet, such as 192.168.0.0 or 192.168.0.255 in 192.168.0.0/24.

Examples:

192.168.0.2 192.168.0.10
192.168.0.4 192.168.0.30..192.168.0.60 192.168.0.110..192.168.0.120
192.168.0.110..192.168.0.120 192.168.0.25..192.168.0.30 192.168.0.144

Set this to an IPv6 prefix to enable ovn-northd to automatically assign IPv6 addresses using this prefix. The assigned IPv6 address will be generated using the IPv6 prefix and the MAC address (converted to an IEEE EUI64 identifier) of the port. The IPv6 prefix defined here should be a valid IPv6 address ending with ::.

Examples:

aef0::
bef0:1234:a890:5678::
8230:5678::

Value used to request to assign L2 address only if neither subnet nor ipv6_prefix are specified See External IDs at the beginning of this document.

A port within an L2 logical switch.

The logical port name.

For entities (VMs or containers) that are spawned in the hypervisor, the name used here must match those used in the in the database's table, because hypervisors use as a lookup key to identify the network interface of that entity.

For containers that share a VIF within a VM, the name can be any unique identifier. See Containers, below, for more information.

Specify 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)

A VM (or VIF) interface.

router

A connection to a logical router.

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

A connection to a physical network.

vtep

A port to a logical switch on a VTEP gateway.

external

Represents a logical port which is external and not having an OVS port in the integration bridge. OVN will never receive any traffic from this port or send any traffic to this port. OVN can support native services like DHCPv4/DHCPv6/DNS for this port. If is defined, ovn-controller running in the master chassis of the HA chassis group will bind this port to provide these native services. It is expected that this port belong to a bridged logical switch (with a localnet port).

It is recommended to use the same HA chassis group for all the external ports of a logical switch. Otherwise, the physical switch might see MAC flap issue when different chassis provide the native services. For example when supporting native DHCPv4 service, DHCPv4 server mac (configured in column in table ) originating from different ports can cause MAC flap issue. The MAC of the logical router IP(s) can also flap if the same HA chassis group is not set for all the external ports of a logical switch.

Below are some of the use cases where external ports can be used.

VMs connected to SR-IOV nics - Traffic from these VMs by passes the kernel stack and local ovn-controller do not bind these ports and cannot serve the native services.
When CMS supports provisioning baremetal servers.

This column provides key/value settings specific to the logical port . The type-specific options are described individually below.

These options apply when is router.

Required. The of the to which this logical switch port is connected.

This is used to send gratuitous ARPs for SNAT and DNAT IP addresses via the localnet port that is attached to the same logical switch as this type router port. This option is specified on a logical switch port that is connected to a gateway router, or a logical switch port that is connected to a distributed gateway port on a logical router.

This must take one of the following forms:

router

Gratuitous ARPs will be sent for all SNAT and DNAT external IP addresses and for all load balancer IP addresses defined on the 's logical router, using the 's MAC address.

This form of is valid for logical switch ports where is the name of a port on a gateway router, or the name of a distributed gateway port.

Supported only in OVN 2.8 and later. Earlier versions required NAT addresses to be manually synchronized.

Ethernet address followed by one or more IPv4 addresses

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 form of is only valid for logical switch ports where is the name of a port on a gateway router.

These options apply when is localnet.

Required. The name of the network to which the localnet port is connected. Each hypervisor, via ovn-controller, uses its local configuration to determine exactly how to connect to this locally accessible network.

These options apply when is l2gateway.

Required. The name of the network to which the l2gateway port is connected. The L2 gateway, via ovn-controller, uses its local configuration to determine exactly how to connect to this network. Required. The chassis on which the l2gateway logical port should be bound to. ovn-controller running on the defined chassis will connect this logical port to the physical network.

These options apply when is vtep.

Required. The name of the VTEP gateway. Required. A logical switch name connected by the VTEP gateway.

These options apply to logical ports with having (empty 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. If set, indicates the maximum rate for data sent from this interface, in bit/s. The traffic will be shaped according to this limit. If set, indicates the maximum burst size for data sent from this interface, in bits.

When a large number of containers are nested within a VM, it may be too expensive to dedicate a VIF to each container. OVN can use VLAN tags to support such cases. Each container is assigned a VLAN ID and each packet that passes between the hypervisor and the VM is tagged with the appropriate ID for the container. Such VLAN IDs never appear on a physical wire, even inside a tunnel, so they need not be unique except relative to a single VM on a hypervisor.

These columns are used for VIFs that represent nested containers using shared VIFs. For VMs and for containers that have dedicated VIFs, they are empty.

The VM interface through which the nested container sends its network traffic. This must match the column for some other .

The VLAN tag in the network traffic associated with a container's network interface. The client can request ovn-northd to allocate a tag that is unique within the scope of a specific parent (specified in ) by setting a value of 0 in this column. The allocated value is written by ovn-northd in the column. (Note that these tags are allocated and managed locally in ovn-northd, so they cannot be reconstructed in the event that the database is lost.) The client can also request a specific non-zero tag and ovn-northd will honor it and copy that value to the column.

When is set to localnet or l2gateway, this can be set to indicate 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.

The VLAN tag allocated by ovn-northd based on the contents of the column.

This column is populated by ovn-northd, rather than by the CMS plugin as is most of this database. When a logical port is bound to a physical location in the OVN Southbound database table, ovn-northd sets this column to true; otherwise, or if the port becomes unbound later, it sets it to false. This allows the CMS to wait for a VM's (or container's) networking to become active before it allows the VM (or container) to start.

Logical ports of router type are an exception to this rule. They are considered to be always up, that is this column is always set to true.

This column is used to administratively set port state. If this column is empty or is set to true, the port is enabled. If this column is set to false, the port is disabled. A disabled port has all ingress and egress traffic dropped.

Addresses owned by the logical port.

Each element in the set must take one of the following forms:

Ethernet address followed by zero or more IPv4 or IPv6 addresses (or both)

An Ethernet address defined is owned by the logical port. Like a physical Ethernet NIC, a logical port ordinarily has a single fixed Ethernet address.

When a OVN logical switch processes a unicast Ethernet frame whose destination MAC address is in a logical port's column, it delivers it only to that port, as if a MAC learning process had learned that MAC address on the port.

If IPv4 or IPv6 address(es) (or both) are defined, it indicates that the logical port owns the given IP addresses.

If IPv4 address(es) are defined, the OVN logical switch uses this information to synthesize responses to ARP requests without traversing the physical network. The OVN logical router connected to the logical switch, if any, uses this information to avoid issuing ARP requests for logical switch ports.

Note that the order here is important. The Ethernet address must be listed before the IP address(es) if defined.

Examples:

80:fa:5b:06:72:b7: This indicates that the logical port owns the above mac address.
80:fa:5b:06:72:b7 10.0.0.4 20.0.0.4: This indicates that the logical port owns the mac address and two IPv4 addresses.
80:fa:5b:06:72:b7 fdaa:15f2:72cf:0:f816:3eff:fe20:3f41: This indicates that the logical port owns the mac address and 1 IPv6 address.
80:fa:5b:06:72:b7 10.0.0.4 fdaa:15f2:72cf:0:f816:3eff:fe20:3f41: This indicates that the logical port owns the mac address and 1 IPv4 address and 1 IPv6 address.

unknown

This indicates that the logical port has an unknown set of Ethernet addresses. When an OVN logical switch processes a unicast Ethernet frame whose destination MAC address is not in any logical port's column, it delivers it to the port (or ports) whose columns include unknown.

dynamic

Use this keyword to make ovn-northd generate a globally unique MAC address and choose an unused IPv4 address with the logical port's subnet and store them in the port's column. ovn-northd will use the subnet specified in in the port's .

Ethernet address followed by keyword "dynamic"

The keyword dynamic after the MAC address indicates that ovn-northd should choose an unused IPv4 address from the logical port's subnet and store it with the specified MAC in the port's column. ovn-northd will use the subnet specified in in the port's table.

Examples:

80:fa:5b:06:72:b7 dynamic: This indicates that the logical port owns the specified MAC address and ovn-northd should allocate an unused IPv4 address for the logical port from the corresponding logical switch subnet.

Keyword "dynamic" followed by an IPv4/IPv6 address

The keyword dynamic followed by an IPv4/IPv6 address indicates that ovn-northd should choose a dynamic ethernet address and use the provided IPv4/IPv6 address as network address.

Examples:

dynamic 192.168.0.1 2001::1: This indicates that ovn-northd should allocate a unique MAC address and use the provided IPv4/IPv6 address for the related port

router

Accepted only when is router. This indicates that the Ethernet, IPv4, and IPv6 addresses for this logical switch port should be obtained from the connected logical router port, as specified by router-port in .

The resulting addresses are used to populate the logical switch's destination lookup, and also for the logical switch to generate ARP and ND replies.

If the connected logical router port has a redirect-chassis specified and the logical router has rules specified in with , then those addresses are also used to populate the switch's destination lookup.

Supported only in OVN 2.7 and later. Earlier versions required router addresses to be manually synchronized.

Addresses assigned to the logical port by ovn-northd, if dynamic is specified in . Addresses will be of the same format as those that populate the column. Note that dynamically assigned addresses are constructed and managed locally in ovn-northd, so they cannot be reconstructed in the event that the database is lost.

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.

Each element in the set must begin with one Ethernet address. This would restrict the host to sending packets from and receiving packets to the ethernet addresses defined in the logical port's column. It also restricts the inner source MAC addresses that the host may send in ARP and IPv6 Neighbor Discovery packets. The host is always allowed to receive packets to multicast and broadcast Ethernet addresses.

Each element in the set may additionally contain one or more IPv4 or IPv6 addresses (or both), with optional masks. If a mask is given, it must be a CIDR mask. In addition to the restrictions described for Ethernet addresses above, such an element restricts the IPv4 or IPv6 addresses from which the host may send and to which it may receive packets to the specified addresses. A masked address, if the host part is zero, indicates that the host is allowed to use any address in the subnet; if the host part is nonzero, the mask simply indicates the size of the subnet. In addition:

If any IPv4 address is given, the host is also allowed to receive packets to the IPv4 local broadcast address 255.255.255.255 and to IPv4 multicast addresses (224.0.0.0/4). If an IPv4 address with a mask is given, the host is also allowed to receive packets to the broadcast address in that specified subnet.

If any IPv4 address is given, the host is additionally restricted to sending ARP packets with the specified source IPv4 address. (RARP is not restricted.)
If any IPv6 address is given, the host is also allowed to receive packets to IPv6 multicast addresses (ff00::/8).

If any IPv6 address is given, the host is additionally restricted to sending IPv6 Neighbor Discovery Solicitation or Advertisement packets with the specified source address or, for solicitations, the unspecified address.

If an element includes an IPv4 address, but no IPv6 addresses, then IPv6 traffic is not allowed. If an element includes an IPv6 address, but no IPv4 address, then IPv4 and ARP traffic is not allowed.

This column uses the same lexical syntax as the column in the OVN Southbound database's table. Multiple addresses within an element may be space or comma separated.

This column is provided as a convenience to cloud management systems, but all of the features that it implements can be implemented as ACLs using the table.

Examples:

80:fa:5b:06:72:b7: The host may send traffic from and receive traffic to the specified MAC address, and to receive traffic to Ethernet multicast and broadcast addresses, but not otherwise. The host may not send ARP or IPv6 Neighbor Discovery packets with inner source Ethernet addresses other than the one specified.
80:fa:5b:06:72:b7 192.168.1.10/24: This adds further restrictions to the first example. The host may send IPv4 packets from or receive IPv4 packets to only 192.168.1.10, except that it may also receive IPv4 packets to 192.168.1.255 (based on the subnet mask), 255.255.255.255, and any address in 224.0.0.0/4. The host may not send ARPs with a source Ethernet address other than 80:fa:5b:06:72:b7 or source IPv4 address other than 192.168.1.10. The host may not send or receive any IPv6 (including IPv6 Neighbor Discovery) traffic.
"80:fa:5b:12:42:ba", "80:fa:5b:06:72:b7 192.168.1.10/24": The host may send traffic from and receive traffic to the specified MAC addresses, and to receive traffic to Ethernet multicast and broadcast addresses, but not otherwise. With MAC 80:fa:5b:12:42:ba, the host may send traffic from and receive traffic to any L3 address. With MAC 80:fa:5b:06:72:b7, the host may send IPv4 packets from or receive IPv4 packets to only 192.168.1.10, except that it may also receive IPv4 packets to 192.168.1.255 (based on the subnet mask), 255.255.255.255, and any address in 224.0.0.0/4. The host may not send or receive any IPv6 (including IPv6 Neighbor Discovery) traffic.

This column defines the DHCPv4 Options to be included by the ovn-controller when it replies to the DHCPv4 requests. Please see the table. This column defines the DHCPv6 Options to be included by the ovn-controller when it replies to the DHCPv6 requests. Please see the table. References a row in the OVN Northbound database's table. It indicates the HA chassis group to use if the is set to external. If is not external, this column is ignored.

This column gives an optional human-friendly name for the port. This name has no special meaning or purpose other than to provide convenience for human interaction with the northbound database.

Neutron copies this from its own port object's name. (Neutron ports do are not assigned human-friendly names by default, so it will often be empty.)

See External IDs at the beginning of this document.

The ovn-northd program copies all these pairs into the column of the table in database.

Each row in this table represents a named set of addresses. An address set may contain Ethernet, IPv4, or IPv6 addresses with optional bitwise or CIDR masks. Address set may ultimately be used in ACLs to compare against fields such as ip4.src or ip6.src. A single address set must contain addresses of the same type. As an example, the following would create an address set with three IP addresses:

      ovn-nbctl create Address_Set name=set1 addresses='10.0.0.1 10.0.0.2 10.0.0.3'

Address sets may be used in the column of the table. For syntax information, see the details of the expression language used for the column in the table of the database.

A name for the address set. Names are ASCII and must match [a-zA-Z_.][a-zA-Z_.0-9]*. The set of addresses in string form. See External IDs at the beginning of this document.

Each row in this table represents a named group of logical switch ports.

Port groups may be used in the column of the table. For syntax information, see the details of the expression language used for the column in the table of the database.

For each port group, there are two address sets generated to the table of the database, containing the IP addresses of the group of ports, one for IPv4, and the other for IPv6, with being the of the followed by a suffix _ip4 for IPv4 and _ip6 for IPv6. The generated address sets can be used in the same way as regular address sets in the column of the table. For syntax information, see the details of the expression language used for the column in the table of the database.

A name for the port group. Names are ASCII and must match [a-zA-Z_.][a-zA-Z_.0-9]*. The logical switch ports belonging to the group in uuids. Access control rules that apply to the port group. Applying an ACL to a port group has the same effect as applying the ACL to all logical lswitches that the ports of the port group belong to. See External IDs at the beginning of this document.

Each row represents one load balancer.

A name for the load balancer. This name has no special meaning or purpose other than to provide convenience for human interaction with the ovn-nb database.

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. If the destination IP address (and port number) of a packet leaving a container or a VM matches the virtual IP address (and port number) provided here as a key, then OVN will statefully replace the destination IP address by one of the provided IP address (and port number) in this map as a value. IPv4 and IPv6 addresses are supported for load balancing; however a VIP of one address family may not be mapped to a destination IP address of a different family. If specifying an IPv6 address with a port, the address portion must be enclosed in square brackets. Examples for keys are "192.168.1.4" and "[fd0f::1]:8800". Examples for value are "10.0.0.1, 10.0.0.2" and "20.0.0.10:8800, 20.0.0.11:8800".

When the Load_Balancer is added to the logical_switch, the VIP has to be in a different subnet than the one used for the logical_switch. Since VIP is in a different subnet, you should connect your logical switch to either a OVN logical router or a real router (this is because the client can now send a packet with VIP as the destination IP address and router's mac address as the destination MAC address).

Valid protocols are tcp or udp. 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.

See External IDs at the beginning of this document.

Each row in this table represents one ACL rule for a logical switch or a port group that points to it through its column. The column for the highest- matching row in this table determines a packet's treatment. If no row matches, packets are allowed by default. (Default-deny treatment is possible: add a rule with 0, 1 as , and deny as .)

The ACL rule's priority. Rules with numerically higher priority take precedence over those with lower. If two ACL rules with the same priority both match, then the one actually applied to a packet is undefined.

Return traffic from an allow-related flow is always allowed and cannot be changed through an ACL.

Direction of the traffic to which this rule should apply:

from-lport: Used to implement filters on traffic arriving from a logical port. These rules are applied to the logical switch's ingress pipeline.
to-lport: Used to implement filters on traffic forwarded to a logical port. These rules are applied to the logical switch's egress pipeline.

The packets that the ACL should match, in the same expression language used for the column in the OVN Southbound database's table. The outport logical port is only available in the to-lport direction (the inport is available in both directions).

By default all traffic is allowed. When writing a more restrictive policy, it is important to remember to allow flows such as ARP and IPv6 neighbor discovery packets.

Note that you can not create an ACL matching on a port with type=router or type=localnet.

The action to take when the ACL rule matches:

allow: Forward the packet.
allow-related: Forward the packet and related traffic (e.g. inbound replies to an outbound connection).
drop: Silently drop the packet.
reject: Drop the packet, replying with a RST for TCP or ICMPv4/ICMPv6 unreachable message for other IPv4/IPv6-based protocols.

These columns control whether and how OVN logs packets that match an ACL.

If set to true, packets that match the ACL will trigger a log message on the transport node or nodes that perform ACL processing. Logging may be combined with any .

If set to false, the remaining columns in this group have no significance.

This name, if it is provided, is included in log records. It provides the administrator and the cloud management system a way to associate a log record with a particular ACL.

The severity of the ACL. The severity levels match those of syslog, in decreasing level of severity: alert, warning, notice, info, or debug. When the column is empty, the default is info.

The name of a meter to rate-limit log messages for the ACL. The string must match the column of a row in the table. By default, log messages are not rate-limited.

See External IDs at the beginning of this document.

Each row represents one L3 logical router.

The router's ports. Zero or more static routes for the router. Zero or more routing policies for the router. This column is used to administratively set router state. If this column is empty or is set to true, the router is enabled. If this column is set to false, the router is disabled. A disabled router has all ingress and egress traffic dropped. One or more NAT rules for the router. NAT rules only work on Gateway routers, and on distributed routers with one logical router port with a redirect-chassis specified. Load balance a virtual ip address to a set of logical port ip addresses. Load balancer rules only work on the Gateway routers.

These columns provide names for the logical router. From OVN's perspective, these names have no special meaning or purpose other than to provide convenience for human interaction with the northbound database. There is no requirement for the name to be unique. (For a unique identifier for a logical router, use its row UUID.)

(Originally, was intended to serve the purpose of a human-friendly name, but the Neutron integration used it to uniquely identify its own router object, in the format neutron-uuid. Later on, Neutron started propagating the friendly name of a router as . Perhaps this can be cleaned up someday.)

A name for the logical router. Another name for the logical router.

Additional options for the logical router.

If set, indicates that the logical router in question is a Gateway router (which is centralized) and resides in the set chassis. The same value is also used by ovn-controller to uniquely identify the chassis in the OVN deployment and comes from external_ids:system-id in the Open_vSwitch table of Open_vSwitch database.

The Gateway router can only be connected to a distributed router via a switch if SNAT and DNAT are to be configured in the Gateway router.

If set, indicates the IP address to use to force SNAT a packet that has already been DNATed in the gateway router. When multiple gateway routers are configured, a packet can potentially enter any of the gateway router, get DNATted and eventually reach the logical switch port. For the return traffic to go back to the same gateway router (for unDNATing), the packet needs a SNAT in the first place. This can be achieved by setting the above option with a gateway specific IP address.

If set, indicates the IP address to use to force SNAT a packet that has already been load-balanced in the gateway router. When multiple gateway routers are configured, a packet can potentially enter any of the gateway routers, get DNATted as part of the load- balancing and eventually reach the logical switch port. For the return traffic to go back to the same gateway router (for unDNATing), the packet needs a SNAT in the first place. This can be achieved by setting the above option with a gateway specific IP address.

See External IDs at the beginning of this document.

Each row in this table represents one QoS rule for a logical switch that points to it through its column. Two types of QoS are supported: DSCP marking and metering. A with the highest- will have QoS applied to it. If the column is specified, then matching packets will have DSCP marking applied. If the column is specified, then matching packets will have metering applied. and are not exclusive, so both marking and metering by defined for the same QoS entry. If no row matches, packets will not have any QoS applied.

The QoS rule's priority. Rules with numerically higher priority take precedence over those with lower. If two QoS rules with the same priority both match, then the one actually applied to a packet is undefined.

The value of this field is similar to column in the OVN Northbound database's table.

The packets that the QoS rules should match, in the same expression language used for the column in the OVN Southbound database's table. The outport logical port is only available in the to-lport direction (the inport is available in both directions).

When specified, matching flows will have DSCP marking applied.

dscp: The value of this action should be in the range of 0 to 63 (inclusive).

When specified, matching packets will have bandwidth metering applied. Traffic over the limit will be dropped.

rate: The value of rate limit in kbps.
burst: The value of burst rate limit in kilobits. This is optional and needs to specify the rate.

See External IDs at the beginning of this document.

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

A name for this meter.

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

The unit for and parameters in the entry. kbps specifies kilobits per second, and pktps specifies packets per second.

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.

See External IDs at the beginning of this document.

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 column in the table.

The action to execute when this band matches. The only supported action is drop.

The rate limit for this band, in kilobits per second or bits per second, depending on whether the parent entry's column specified kbps or pktps.

The maximum burst allowed for the band in kilobits or packets, depending on whether kbps or pktps was selected in the parent entry's column. If the size is zero, the switch is free to select some reasonable value depending on its configuration.

See External IDs at the beginning of this document.

A port within an L3 logical router.

Exactly one row must reference a given logical router port.

A name for the logical router port.

In addition to provide convenience for human interaction with the northbound database, this column is used as reference by its patch port in or another logical router port in .

This column is ignored if the column . is set.

Several can be referenced for a given logical router port. A single is functionally equivalent to setting . Refer to the description of for additional details on gateway handling.

Defining more than one will enable gateway high availability. Only one gateway will be active at a time. OVN chassis will use BFD to monitor connectivity to a gateway. If connectivity to the active gateway is interrupted, another gateway will become active. The column specifies the order that gateways will be chosen by OVN.

If set, this indicates that this logical router port represents a distributed gateway port that connects this router to a logical switch with a localnet port. There may be at most one such logical router port on each logical router. The HA chassis which are part of the HA chassis group will provide the gateway high availability. Please see the for more details.

When this column is set, the column will be ignored.

The IP addresses and netmasks of the router. For example, 192.168.0.1/24 indicates that the router's IP address is 192.168.0.1 and that packets destined to 192.168.0.x should be routed to this port.

A logical router port always adds a link-local IPv6 address (fe80::/64) automatically generated from the interface's MAC address using the modified EUI-64 format.

The Ethernet address that belongs to this router port. This column is used to administratively set port state. If this column is empty or is set to true, the port is enabled. If this column is set to false, the port is disabled. A disabled port has all ingress and egress traffic dropped.

This column defines the IPv6 ND RA address mode and ND MTU Option to be included by ovn-controller when it replies to the IPv6 Router solicitation requests.

The address mode to be used for IPv6 address configuration. The supported values are:

slaac: Address configuration using Router Advertisement (RA) packet. The IPv6 prefixes defined in the table's column will be included in the RA's ICMPv6 option - Prefix information.
dhcpv6_stateful: Address configuration using DHCPv6.
dhcpv6_stateless: Address configuration using Router Advertisement (RA) packet. Other IPv6 options are provided by DHCPv6.

The recommended MTU for the link. Default is 0, which means no MTU Option will be included in RA packet replied by ovn-controller. Per RFC 2460, the mtu value is recommended no less than 1280, so any mtu value less than 1280 will be considered as no MTU Option. If set to true, then this router interface will send router advertisements periodically. The default is false. The maximum number of seconds to wait between sending periodic router advertisements. This option has no effect if is false. The default is 600. The minimum number of seconds to wait between sending periodic router advertisements. This option has no effect if is false. The default is one-third of , i.e. 200 seconds if that key is unset.

Additional options for the logical router port.

Even when a redirect-chassis is specified, the logical router port still effectively resides on each chassis. However, due to the implications of the use of L2 learning in the physical network, as well as the need to support advanced features such as one-to-many NAT (aka IP masquerading), a subset of the logical router processing is handled in a centralized manner on the specified redirect-chassis.

When this option is specified, the peer logical switch port's must be set to router. With this setting, the s specified in NAT rules are automatically programmed in the peer logical switch's destination lookup on the chassis where the resides. In addition, the logical router's MAC address is automatically programmed in the peer logical switch's destination lookup flow on the redirect-chassis.

When this option is specified and it is desired to generate gratuitous ARPs for NAT addresses, then the peer logical switch port's should be set to router.

While is still supported for backwards compatibility, it is now preferred to specify one or more instead. It is functionally equivalent, but allows you to specify multiple chassis to enable high availability.

Generally routing is distributed in OVN. The packet from a logical port which needs to be routed hits the router pipeline in the source chassis. For the East-West traffic, the packet is sent directly to the destination chassis. For the outside traffic the packet is sent to the gateway chassis.

When this option is set, OVN considers this only if

The logical router to which this logical router port belongs to has a distributed gateway port.
The peer's logical switch has a localnet port (representing a VLAN tagged network)

When this option is set to true, then the packet which needs to be routed hits the router pipeline in the chassis hosting the distributed gateway router port. The source chassis pushes out this traffic via the localnet port. With this the East-West traffic is no more distributed and will always go through the gateway chassis.

Without this option set, for any traffic destined to outside from a logical port which belongs to a logical switch with localnet port, the source chassis will send the traffic to the gateway chassis via the tunnel port instead of the localnet port and this could cause MTU issues.

A given router port serves one of two purposes:

To attach a logical switch to a logical router. A logical router port of this type is referenced by exactly one of type router. The value of is set as router-port in column of . In this case column is empty.
To connect one logical router to another. This requires a pair of logical router ports, each connected to a different router. Each router port in the pair specifies the other in its column. No refers to the router port.

For a router port used to connect two logical routers, this identifies the other router port in the pair by .

For a router port attached to a logical switch, this column is empty.

See External IDs at the beginning of this document.

Each record represents a static route.

When multiple routes match a packet, the longest-prefix match is chosen. For a given prefix length, a dst-ip route is preferred over a src-ip route.

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

If it is specified, this setting describes the policy used to make routing decisions. This setting must be one of the following strings:

src-ip: This policy sends the packet to the when the packet's source IP address matches .
dst-ip: This policy sends the packet to the when the packet's destination IP address matches .

If not specified, the default is dst-ip.

Nexthop IP address for this route. Nexthop IP address should be the IP address of a connected router port or the IP address of a logical port.

The name of the via which the packet needs to be sent out. This is optional and when not specified, OVN will automatically figure this out based on the . When this is specified and there are multiple IP addresses on the router port and none of them are in the same subnet of , OVN chooses the first IP address as the one via which the is reachable.

See External IDs at the beginning of this document.

Each row in this table represents one routing policy for a logical router that points to it through its column. The column for the highest- matching row in this table determines a packet's treatment. If no row matches, packets are allowed by default. (Default-deny treatment is possible: add a rule with 0, 1 as , and drop as .)

The routing policy's priority. Rules with numerically higher priority take precedence over those with lower. A rule is uniquely identified by the priority and match string.

The packets that the routing policy should match, in the same expression language used for the column in the OVN Southbound database's table.

By default all traffic is allowed. When writing a more restrictive policy, it is important to remember to allow flows such as ARP and IPv6 neighbor discovery packets.

The action to take when the routing policy matches:

allow: Forward the packet.
drop: Silently drop the packet.
reroute: Reroute packet to .

Next-hop IP address for this route, which should be the IP address of a connected router port or the IP address of a logical port.

Each record represents a NAT rule.

Type of the NAT rule.

When is dnat, the externally visible IP address is DNATted to the IP address in the logical space.
When is snat, IP packets with their source IP address that either matches the IP address in or is in the network provided by is SNATed into the IP address in .
When is dnat_and_snat, the externally visible IP address is DNATted to the IP address in the logical space. In addition, IP packets with the source IP address that matches is SNATed into the IP address in .

An IPv4 address.

A MAC address.

This is only used on the gateway port on distributed routers. This must be specified in order for the NAT rule to be processed in a distributed manner on all chassis. If this is not specified for a NAT rule on a distributed router, then this NAT rule will be processed in a centralized manner on the gateway port instance on the redirect-chassis.

This MAC address must be unique on the logical switch that the gateway port is attached to. If the MAC address used on the is globally unique, then that MAC address can be specified as this .

An IPv4 network (e.g 192.168.1.0/24) or an IPv4 address.

The name of the logical port where the resides.

This is only used on distributed routers. This must be specified in order for the NAT rule to be processed in a distributed manner on all chassis. If this is not specified for a NAT rule on a distributed router, then this NAT rule will be processed in a centralized manner on the gateway port instance on the redirect-chassis.

See External IDs at the beginning of this document.

OVN implements native DHCPv4 support which caters to the common use case of providing an IPv4 address to a booting instance by providing stateless replies to DHCPv4 requests based on statically configured address mappings. To do this it allows a short list of DHCPv4 options to be configured and applied at each compute host running ovn-controller.

OVN also implements native DHCPv6 support which provides stateless replies to DHCPv6 requests.

The DHCPv4/DHCPv6 options will be included if the logical port has its IP address in this .

The CMS should define the set of DHCPv4 options as key/value pairs in the column of this table. For ovn-controller to include these DHCPv4 options, the of should refer to an entry in this table.

The following options must be defined.

The IP address for the DHCP server to use. This should be in the subnet of the offered IP. This is also included in the DHCP offer as option 54, ``server identifier.'' The Ethernet address for the DHCP server to use.

The offered lease time in seconds,

The DHCPv4 option code for this option is 51.

Below are the supported DHCPv4 options whose values are an IPv4 address, e.g. 192.168.1.1. Some options accept multiple IPv4 addresses enclosed within curly braces, e.g. {192.168.1.2, 192.168.1.3}. Please refer to RFC 2132 for more details on DHCPv4 options and their codes.

The IP address of a gateway for the client to use. This should be in the subnet of the offered IP. The DHCPv4 option code for this option is 3.

The DHCPv4 option code for this option is 1.

The DHCPv4 option code for this option is 6.

The DHCPv4 option code for this option is 7.

The DHCPv4 option code for this option is 9.

The DHCPv4 option code for this option is 16.

The DHCPv4 option code for this option is 21.

The DHCPv4 option code for this option is 32.

The DHCPv4 option code for this option is 41.

The DHCPv4 option code for this option is 42.

The DHCPv4 option code for this option is 66.

The DHCPv4 option code for this option is 121.

This option can contain one or more static routes, each of which consists of a destination descriptor and the IP address of the router that should be used to reach that destination. Please see RFC 3442 for more details.

Example: {30.0.0.0/24,10.0.0.10, 0.0.0.0/0,10.0.0.1}

The DHCPv4 option code for this option is 249. This option is similar to classless_static_route supported by Microsoft Windows DHCPv4 clients.

These options accept a Boolean value, expressed as 0 for false or 1 for true.

The DHCPv4 option code for this option is 19.

The DHCPv4 option code for this option is 31.

The DHCPv4 option code for this option is 36.

These options accept a nonnegative integer value.

The DHCPv4 option code for this option is 23. The DHCPv4 option code for this option is 37. The DHCPv4 option code for this option is 26. This specifies the time interval from address assignment until the client begins trying to renew its address. The DHCPv4 option code for this option is 58. This specifies the time interval from address assignment until the client begins trying to rebind its address. The DHCPv4 option code for this option is 59.

These options accept a string value.

The DHCPv4 option code for this option is 252. This option is used as part of web proxy auto discovery to provide a URL for a web proxy.

The DHCPv4 option code for this option is 67. This option is used to identify a bootfile.

The DHCPv4 option code for this option is 210. In PXELINUX' case this option is used to set a common path prefix, instead of deriving it from the bootfile name.

The DHCPv4 option code for this option is 150. The option contains one or more IPv4 addresses that the client MAY use. This option is Cisco proprietary, the IEEE standard that matches with this requirement is option 66 (tftp_server).

OVN also implements native DHCPv6 support. The CMS should define the set of DHCPv6 options as key/value pairs. The define DHCPv6 options will be included in the DHCPv6 response to the DHCPv6 Solicit/Request/Confirm packet from the logical ports having the IPv6 addresses in the .

The following options must be defined.

The Ethernet address for the DHCP server to use. This is also included in the DHCPv6 reply as option 2, ``Server Identifier'' to carry a DUID identifying a server between a client and a server. ovn-controller defines DUID based on Link-layer Address [DUID-LL].

Below are the supported DHCPv6 options whose values are an IPv6 address, e.g. aef0::4. Some options accept multiple IPv6 addresses enclosed within curly braces, e.g. {aef0::4, aef0::5}. Please refer to RFC 3315 for more details on DHCPv6 options and their codes.

The DHCPv6 option code for this option is 23. This option specifies the DNS servers that the VM should use.

These options accept string values.

The DHCPv6 option code for this option is 24. This option specifies the domain search list the client should use to resolve hostnames with DNS.

Example: "ovn.org".

This option specifies the OVN native DHCPv6 will work in stateless mode, which means OVN native DHCPv6 will not offer IPv6 addresses for VM/VIF ports, but only reply other configurations, such as DNS and domain search list. When setting this option with string value "true", VM/VIF will configure IPv6 addresses by stateless way. Default value for this option is false.

See External IDs at the beginning of this document.

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.

Connection methods for clients.

The following connection methods are currently supported:

ssl:host[:port]

The specified SSL port on the host at 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 specified via command-line options or the 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:host[:port]

The specified TCP port on the host at the given host, which can either be a DNS name (if built with unbound library) or an IP address. 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 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 address, is specified, then connections are restricted to the resolved or specified local IPaddress (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) addresses. A valid SSL configuration must be provided when this form is used, this can be specified either via command-line options or the 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][:host]

Listens for 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 address, 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 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 values must be unique. Duplicate values yield unspecified results.

Maximum number of milliseconds to wait between connection attempts. Default is implementation-specific. 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.

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

When specifies a connection method that listens for inbound connections (e.g. ptcp: or punix:), both and may also be updated while the remaining key-value pairs are omitted.

On the other hand, when 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.

true if currently connected to this client, false otherwise. 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.

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.

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. The amount of time since this client last disconnected from the database (in seconds). Value is empty if client has never disconnected. Space-separated list of the names of OVSDB locks that the connection holds. Omitted if the connection does not hold any locks. 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. 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. When 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. When is ptcp: or pssl:, this is the TCP port on which the OVSDB server is listening. (This is particularly useful when specifies a port of 0, allowing the kernel to choose any available port.) The overall purpose of these columns is described under

Common
      Columns

at the beginning of this document.

Each row in this table stores the DNS records. The table's references these records.

Key-value pair of DNS records with DNS query name as the key and value as a string of IP address(es) separated by comma or space.

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

See External IDs at the beginning of this document.

SSL configuration for ovn-nb database access. Name of a PEM file containing the private key used as the switch's identity for SSL connections to the controller. 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. Name of a PEM file containing the CA certificate used to verify that the switch is connected to a trustworthy controller. 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. List of SSL protocols to be enabled for SSL connections. The default when this option is omitted is TLSv1,TLSv1.1,TLSv1.2. 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. The overall purpose of these columns is described under

Common
      Columns

at the beginning of this document.

Association of one or more chassis to a logical router port. The traffic going out through an specific router port will be redirected to a chassis, or a set of them in high availability configurations. A single is equivalent to setting . Using allows associating multiple prioritized chassis with a single logical router port.

Name of the .

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

Name of the chassis that we want to redirect traffic through for the associated logical router port. The value must match the column of the table in the database.

This is the priority of a chassis among all belonging to the same logical router port.

Reserved for future use. See External IDs at the beginning of this document.

Table representing a group of chassis which can provide High availability services. Each chassis in the group is represented by the table . The HA chassis with highest priority will be the master of this group. If the master chassis failover is detected, the HA chassis with the next higher priority takes over the responsibility of providing the HA. If a distributed gateway router port references a row in this table, then the master HA chassis in this group provides the gateway functionality.

Name of the . Name should be unique. A list of HA chassis which belongs to this group. See External IDs at the beginning of this document.

Name of the chassis which is part of the HA chassis group. The value must match the column of the table in the database.

Priority of the chassis. Chassis with highest priority will be the master.

See External IDs at the beginning of this document.