Configuring a router ID

When router ospf3 enable is used to enable OSPFv3 on a routing switch, the following message appears if an IPv4 network or loopback address is not detected: 

Either an IPv4 loopback address or a router ID needs to be configured before enabling OSPFv3. 
Do you want to continue? [y/n]
Procedure
  1. Type N (no) to keep OSPFv3 disabled.
  2. Type Y to enable OSPFv3 without a router ID. However, without the ID, OSPFv3 traffic is not routed. In this case do one of the following:

    • Configure an IPv4 address on a loopback interface or VLAN.

    • Manually configure a router ID on the routing switch.