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New Member

Secondary IP addressing

I'm having a problem with secondary IP addressing, the situation is as follows. 3620 with e1/0 with the primary of 10.56.64.1 255.255.224.0 with the secondary of 10.3.0.1 255.255.0.0 going into a switch (3com I believe) then to the 2600 with the E0 primary of 10.3.0.5 and no secondary. All routing between the two stops working. Change the primary on the 3600 back to 10.3.0.1 as primary and all is good. Any suggestions on how to get this to work?

5 REPLIES
New Member

Re: Secondary IP addressing

For this to work, the secondary addresses on the interface must be in a valid subnet underneath the primary addresses' subnet.

10.56.64.1/19 is a valid subnet of 10.3.0.1/16.

but

10.3.0.1/16 is not a valid subnet of 10.56.64.1/19.

You might be able to set up proxy-arp and/or a static route on the 3620 to get it to work but unless there's a specific reason you *must* have 10.56.64.1/19 as primary you should use 10.3.0.1/16 for the primary address.

New Member

Re: Secondary IP addressing

What routing protocol are you using? OSPF will fail because you can't form adjacencies on secondary IPs. There are other issues that could cause RPs to fail in this case since your primarys don't live on the same subnet.

Mick.

New Member

Re: Secondary IP addressing

I'm using EIGRP, The situation is that we are readdressing everything and all links work but this one. I think trying the 10.3.0.1 as the primary may do it. I'll be checking this after hours today. I'll also check the fact that I missed an intermediate router when doing the secondary may have something to do with this but is doubt it.

New Member

Re: Secondary IP addressing

I may have faced a similar situation years ago. EIGRP seemed to ignore connected secondary networks. Try "redistribute connected" under EIGRP!

New Member

Re: Secondary IP addressing

Sorry I didn't post last night, You all have helped me solve the problem. It was actualy to 10.3.0.1 needed to be primary. this worked like a charm and no downtime on the link while it was bieng done. I owe all of you a big thanks. In some testing we may have the problem of the EIGRP not showing the secondaries but nothing on the livewire. The redistribute is already in place. The rest is up to the site infrastructure guys. again THANKS!!!!

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