Separate OSPF Area Zeros

[jlizzio]

Hi Everyone,

I have a question that I cannot seem to find the answer to in any documentation. 

We acquired a company that is running OSPF as their IGP. We too are running OSPF.

Both companies are obviously using area 0 so the question is how to best connect these two entities together. I know I can use another routing protocol and redistribute but ideally I'd like to stay with OSPF. So could I have Company A AREA 0 - COMPANY A AREA 300 - connect to Company B AREA 0 and not have any issues?

I created a lab within Maestro and didn't have any problems but I wanted to see what the communities thoughts were.

Thanks,

-JL

[Julio E. Moisa]

Hi

It is a interesting study case, VRF could be a quick solution while you are migrating all the infrastructure or use static route between both companies. 

[Joseph W. Doherty]

So could I have Company A AREA 0 - COMPANY A AREA 300 - connect to Company B AREA 0 and not have any issues?

Hmm, interesting.  What would concern me, although it's not, what it looks like you have is a partitioned area zero.  That said, what you propose may work, but it makes me nervous, as it's possibly an accident waiting to happen.

If you're using Cisco devices, you can run two OSPF processes on routers with a connection to both company networks and redistribute between them.

[jlizzio]

It makes me nervous as well. 

I could build a tunnel between the two companies using a virtual interface and tie both ends of the tunnel to area zero, however I really don't like the idea of adding company B to my area zero as I don't have full control of their infrastructure. Maybe the best thing to do is run separate OSPF processes and redistribute. 

[Richard Burts]

As you get the companies integrated then you probably want to think about using an OSPF virtual link to tie the area zero.  But if at this point you do not have full control then you definitely want to run separate OSPF processes and redistribute.

HTH

Rick 

[trfinkenstadt]

as long as you aren't using an ASR9k (ios-xr) with your OSPF in a VRF.  Then you only get one OSPF process per VRF.  At least as of 5.3.1.