OSPF v3 options

Below is given some illustration that help on how to configure OSPF v3.

OSPF v3 cost

Following example sets the interface output cost. If not set, the value is automatically calculated based on the bandwidth of the interface. By default, cost is set to 1 for a 100MB link.

vrf main
  routing interface eth0_0
    ipv6 ospf6 cost 20

As said before, if not explicitly set, the cost is determined by the bandwidth of the interface. It is possible to impact the cost value by changing the default reference bandwidth used. By default, it is 100MB. Below example illustrates a reference of 1GB.

vrf main
  routing ospf6
    auto-cost 1000

OSPF v3 priority

The interface’s router Priority for election of designated router can be modified, by using following command on routing interface mode.

vrf main
  routing interface eth0_0
    ipv6 ospf6 priority 10

Default value is 1.

OSPF v3 hello interval

Below example illustrates how to set interval for hello messages, per interface.

vrf main
  routing interface eth0_0
    ipv6 ospf6 hello-interval 20

Default value is 10 seconds.

OSPF v3 transmit-delay

Below example illustrates how to configure per interface transmit-delay:

vrf main
  routing interface eth0_0
    ipv6 ospf6 transmit-delay 3

Default value is 1.

Passive interface

This feature should be used when it is required to prevent some router’s interfaces from forming OSPF adjacencies. It may be for instance to include a subnet into the OSPF routing process (and LSD), without actually running OSPF on the interface of the router connected to that subnet. This is useful to announce stub networks instead of external LSA. This is particularly adapted for interfaces that are used as BGP peering links or for customer connectivity.

vrf main
  routing interface eth0_0
    ipv6 ospf6 passive true
    ..
    ..
  routing ospf6
    interface eth0_0 area 0.0.0.0
    ..
    ..

ECMP

There might be some situation in which, for a common destination, OSPF has different paths, of equal cost to reach that destination. In such situation, network traffic may be distributed equally among all the equal cost paths. This situation relies on the ECMP capabilities.