Configuring the Router ID

In OSPFv3, all neighbors are identified by their router ID, not the interface address, as is the case for OSPFv2 broadcast and NBMA links. OSPFv3 initially assigns all routers a router ID based on the highest loopback IP address of the interfaces configured for IP routing. If there is no loopback interface configured then it will be the highest VLAN IP address configured. This unique value, which is included in the hello packet transmitted in Link State Advertisements (LSA), identifies one router to another and helps establish adjacencies among OSPFv3 routers. When you specify an interface as the router ID, this value supersedes the default ID.

Use the router-id command in OSPFv3 configuration mode to override the default router ID.

The following example sets the router ID to 1.1.1.1, overriding the default router ID value:

System(rw)->configure
System(rw-config)->interface loopback 1
System(su-config-intf-loop.0.1)->ip address 2001:a123::1
System(rw-config-intf-loop.0.1)->exit
System(rw-config)->ipv6 router ospf 1
System(rw-config-ospfv3)->router-id 1.1.1.1
System(rw-config-ospfv3)->exit
System(rw-config)->