OSPF Process ID

showint

I have a question regarding ospf process id.

I always configured each router in an ospf domain with different process id. But today I watched a tutorial where a man configured all routers with a single ospf process id (for example 1) in all areas in a multi-area ospf. It got me confused. So I've started searching info about it in google, but found nothing than "OSPF Process ID is a unique number on routers that group a series of OSPF configuration commands under a specific running process". But the definition remained unclear to me.

I would really appreciate it if you could help me with this.

networker050184

It's common practice to set the process ID the same on every router on the network (usually ASN or 1 are the most popular I've seen), but as you have seen from your lab it's not technically required. I think I'd probably kill you if I came onto your network and saw every router with a different process ID though. It would make automation a nightmare! I'd always be typing the wrong number and then you end up with a bunch of orphaned OSPF processes on the routers from typos.... Not a good thing to do.

You can think of the process ID basically like a locally significant identifier so the router knows which OSPF process you are trying to configure, redistribute etc.

showint

Networker, thank You for Your very informative reply to my question!

satishtech

Can we have two ospf process on a single router ?
if yes why is it done ?
I presume that two ospf process on a single Router must
have different process ID's.

networker050184

Yes we can have two OSPF processes and they will use different process IDs. Why would you do this? If you don't want to share routes between the processes for a migration, integration etc.