Configuration guidelines

To enable OSPF on an interface, you can enable OSPF on the network where the interface resides or directly enable OSPF on that interface. If you configure both, the latter takes precedence.

You can specify a global router ID, or specify a router ID when you create an OSPF process.

• If you specify a router ID when you create an OSPF process, any two routers in an AS must have different router IDs. A common practice is to specify the IP address of an interface as the router ID.

• If you specify no router ID when you create the OSPF process, the global router ID is used. As a best practice, specify a router ID when you create the OSPF process.

OSPF supports multiple processes and VPNs.

• To run multiple OSPF processes, you must specify an ID for each process. The process IDs take effect locally and has no influence on packet exchange between routers. Two routers with different process IDs can exchange packets.

• You can configure an OSPF process to run in a specified VPN instance. For more information about VPN, see MPLS Configuration Guide.