This is the documentation for the 21.07 version. Looking for the documentation of the latest version? Have a look here.

OSPF6 Interface ConfigurationΒΆ

OSPF6 must use one or more interfaces to announce itself to neighbors and to receive announcements from neighbors. At least one interface must be configured and active in order to locate neighbors and form an adjacency.


Outside NAT interfaces (ip nat outside) cannot be used as active interfaces in OSPF6! The presence of NAT prevents OSPF6 from properly communicating with neighbors to form a full adjacency.

To configure an interface for use with OSPF6, start in config-frr-ospf6 mode and use the interface <if-name> command to enter config-ospf6-if mode.

tnsr(config)# route dynamic ospf6
tnsr(config-frr-ospf6)# interface <if-name>

config-ospf6-if mode contains the following commands:

advertise prefix-list <name>

Filters route advertisements using the specified prefix list (Dynamic Routing Prefix Lists).

bfd enabled (true|false)

Enable Bidirectional Forwarding Detection for OSPF6 on this interface.

cost outgoing <link-cost>

A manual cost value to apply to this interface, rather than allowing automatic cost calculation to take place.

In situations where multiple paths are possible to the same destination, this allows OSPF6 to prefer one path over another when all else is equal.

dead-interval <time>

Time, in seconds from 1-65535, without communication from a neighbor on this interface before considering it dead. This is also known as the RouterDeadInterval timer in OSPF6. Default value is 40. This timer should be set to the same value for all routers.

hello-interval <interval>

The interval, in seconds from 1-65535, at which this router will send hello messages. This is also known as the HelloInterval timer in OSPF6. Default value is 10. This timer should be set to the same value for all routers.

A lower value will result in faster convergence times, but will consume more resources.

instance-id <value>

An alternate OSPF6 instance identifier for this interface. Typically omitted or set to 0.

mtu <value>

Explicitly configures an MTU value for this interface. This value will override the interface MTU determined automatically by the operating system. Useful in cases where the router is unable to determine the actual interface MTU, for example on virtual interfaces such as those used by IPsec.


When present, OSPF6 will ignore the MTU advertised by neighbors and can still achieve a full adjacency when peers do not have matching MTU values.

network (broadcast|point-to-point)

Manually configures a specific type of network used on a given interface, rather than letting OSPF6 determine the type automatically. This controls how OSPF6 behaves and how it crafts messages when using an interface.


Broadcast networks, such as typical Ethernet networks, allow multiple routers on a segment and OSPF6 can use multicast to send messages to multiple targets at once. OSPF6 assumes that all routers on broadcast networks are directly connected and can communicate without passing through other routers.


A point-to-point network links a single pair of routers. The interface is still capable of broadcast, and OSPF6 will dynamically discover neighbors. With this type of network, OSPF6 disables election of a DR.


Configures this interface as passive. This prevents the interface from actively participating in OSPF6, while still allowing OSPF6 to operate on networks connected to that interface. This is commonly used for local interfaces without other routers attached. OSPF6 will announce networks attached to passive interfaces as stub links.

priority <priority>

A priority value, from 0-255, assigned to this router. When determining which router will become the Designated Router (DR), the router with the highest priority is more likely to be elected as the DR.

The default value is 1. The value 0 is special and will prevent this router from being chosen as DR.

retransmit-interval <interval>

The interval, in seconds from 1-65535, at which this router will retransmit Link State Request and Database Description messages. This is also known as the RxmtInterval timer in OSPF6. Default value is 5.

transmit-delay <delay>

The interval, in seconds from 1-65535, at which this router will transmit LSA messages. This is also known as the InfTransDelay timer in OSPF6. Default value is 1.