Migrate RIP to OSPF

[hutcha4113]

Hi Everyone,

I am currently doing research to setup up OSPF while migrating from RIP V2.  From what I understand I can have both protocols running at the same time - I would just need to set the AD on OSPF to 121 until I am ready to remove RIP.

Based on this RIP configuration:

• Network 10.0.0.0
• Network 172.23.0.0
• Network 172.32.0.0

What would I need to do to setup OSPF for the above?  I am a little confused on the proper commands.

Thanks in advance.

Adam

[Joseph W. Doherty]

There's many OSPF commands, and also OSPF design conditions.  So, difficult to suggest how OSPF should be configured without more information.

If you have questions about specific usage of OSPF commands, youl likely get good advice.

[sasanka1912]

@hutcha4113 

Hi , Porbably below could be some of the steps you can follow for this migration

1.Configure ospf configuration and deploy to all the devices that you need to migrate. Check OSPF IS FULLY CONVERGED and neighbor's are synced.

2.You have to increase the admin distance higher than RIP , so that OSPF will not be preferred until the migration .

3. Once ready , you may remove the distance command from ospf

4.Check the routing table and see if you can see ospf routes including ip ospf neighbors/database .

5.iF all ok, you may remove the RIP from all the devices.

[paul driver]

Hello
One way would be to enabled OSPF but set the seed metric for that routing process to be higher then RIPs seed metric thus you can create your ospf network/adjacencys etc without any outage and still have all your routing running on RIP and when the time comes to migrate simply remove the  temporary applied seed metric from the OSPF process  and the routing should then prefer OSPF over RIP.

Example:
router ospf x
distance ospf intra-area 121 inter-area 150 external 150
network 10.0.0.0 255.0.0.0  area x
network 172.23.0.0 255.255.0.0  area x
network 172.32.0.0 255.255.0.0  area x

All route should still be RIP routes, when you are ready to migrate..

router ospf x
no distance ospf intra-area 121 inter-area 150 external 150
end
clear ip route *

[hutcha4113]

Ok.  I believe that is what I was looking for.  Appreciate all the posts.  Would the Area "x" be the same as the OSPF number I chose?  So for example of I do Router OSPF 23 - then the area is also 23?

I am looking forward to giving this a try.  We plan on testing with one site first to verify, and then setup all the other ones.

[Joseph W. Doherty]

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@hutcha4113 wrote:

Would the Area "x" be the same as the OSPF number I chose?  So for example of I do Router OSPF 23 - then the area is also 23?

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No, they're not related, although for a single area, you could set them the same (except might not be able to use zero for a OSPF process ID).

Of course, also with OSPF, there's special significance to using area zero.  (An OSPF design issue.)

I would suspect, your topology is small enough, you wouldn't need to get into multi-area design issues.

One issue you may need to consider is OSPF costing.

[paul driver]

Hello
I would say no also I believe this is what  @Joseph W. Doherty  was regarding as it all depends on your network topology to how you would create an ospf network - usually depending on how many rtrs you have and how large your route table will be factor on the design but usually a single area 0 (backbone area) would be applicable 
As for the routing process number/name - this can be whatever you want it to be but again usually this has parity on all rtrs in the ospf domain 

[Joseph W. Doherty]

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@paul driver wrote:

Example:
router ospf x
network 10.0.0.0 255.0.0.0  area x
network 172.23.0.0 255.255.0.0  area x
network 172.32.0.0 255.255.0.0  area x

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BTW, what @paul driver shows for network statements, OSPF doesn't necessarily advertise those networks, it uses those statements to select interface IPs to include into OSPF.

network 0.0.0.0 0.0.0.0 area x

Would inject ALL the up/up interfaces on that device (well in same VRF).

Also, by default, interface picked up by a network statement, can form an OSPF adjacency with another OSPF router, which may be exactly what you want, or exactly what you do NOT want.

On the new IOS variants, there another way to include an interface into OSPF.