Cisco Support Community
Showing results for 
Search instead for 
Did you mean: 

Welcome to Cisco Support Community. We would love to have your feedback.

For an introduction to the new site, click here. If you'd prefer to explore, try our test area to get started. And see here for current known issues.

New Member

What, if any, issues are their when connecting OSPF via Nortel to Cisco?

I have been searching on and for answers to this question.

We will possibly be integrating our existing all Cisco based network with a network that has all Nortel. This company is running OSPF.

Currently we are running EIGRP and are weighing our options of moving to OSPF to attain full integration with this company.

What issues are there and are there any guides available for this task?

Also, if this is posted in the wrong area can an Admin please move it to the appropriate area?


Re: What, if any, issues are their when connecting OSPF via Nort

The OSPF timers have to match for ant 2 routers to form an adjacancy and Nortel may use different default values.

Also, since, for an OSPF network to funcion well, it must be carefully designed in terms of areas, with a contiguous area zero and all other areas adjacent to it, and for optimal summerisation, the addressing must be carefully planned so converting your existing network is not a trivial task.

There is a load of examples of OSPF configuration on CCO at the following URL

You could always just redistribute your EIGRP routes to OSPF and vice versa on an edge router rather than converting your network.

Re: What, if any, issues are their when connecting OSPF via Nort

Nortel and Cisco have different default MTU sizes on WAN interfaces by default. OSPF needs the MTU size to be the same else you will see the OSPF adj only get to the database description / exchange state and get stuck there. On the Nortel you can change the OSPF interface value called OSPF MTU Size. This is 1 by default which means to acquire it from the physical interface MTU setting but depending on version of code 'acquire' doesn't always work so I prefer to set both the physical MTU and OSPF MTU to what they really should be.

Make sure the OSPF network types are the same on both router interfaces connecting to one another. Also make sure the OSPF area # is put in like x.x.x.x so you don't end up with area vs If I recall correctly I think BayRS is reverse from Cisco if you just one #. You may also want to configure the OSPF RID on the Nortel if possible. By default it is the first interface IP address configured for OSPF. If you delete it later the RID doesn't change so is the deleted IP address still. This doesn't effect OSPF as the RID just needs to be unique for each router and not an actual IP address.

You may also want to consider taking some security measures (filtering, etc) since this is a different company and you may / may not want all their routes in your network and vice versa. But if it's full integration then maybe this isn't a concern.

That should be all. Let me know if you need more assistance.

New Member

correct... timers should be

correct... timers should be the same. on nortel you can issue the following to get good data.


8600# trace level 6 3

screen on

 ospfProcHello: received on ipa= src_ipa=

ospfProcHello: hello-interval mismatch ipa= other_int=10, my_int=30

ospfProcHello: dead-router mismatch ipa= , other_int=40, my_int=120

Resolve and you'll see it start INIT.