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IP CEF issue

I have two cisco routers currently running ip cef. The gear I have is a 3745 router at the central end and a 2611XM router at the far end. I am load balancing two T1s between them. The WICs are VWIC-2MFT-T1 cards at both sites. The weird problem I am having is this. I am trying to add another T1 to the IP CEF bundle. I have OSPF running on the current T1s and per-packet load-balancing turned on. When I add the new T1 to the router, I add OSPF to the new subnet and make sure that the interface is running ip cef. The WICs that I am using for the new T1 are a VWIC-2MFT-T1 at the central site and a WIC-1DSU-T1 at the remote site. When I turn everything up it looks good in my ip route table on the 3745 router with the VWIC. It now shows that there are 3 routes to the destinations. BUT on the 2611 side with the WIC-1DSU-T1, the sh ip route output shows me that the router is now only using the new single T1 and not load-balancing any traffic over the 2 existing T1s. When I run a sh ip cef <interface> I get that the new WIC has all the CEF info. The cef info for the other 2 T1s off the VWIC show only the attached subnets. They don't have any of the CEF info anymore. I hace tried to clear the cef table, shut down the T1 and restarted but nothing. If I shut the WIC T1 down on the 2611, the cef information now shows load-balancing over the 2 T1s again like it was before. I am not sure if this is a module compatibility issue or a config issue. I was just hoping that someone out there has seen this as well and might know if it might be a bug. I have tried to turn on ip cef distributed in the 2611 router BUT that command is not available for the IOS I am running on it. I am running 12.3(14)T5 IOS on the 2611XM and 12.3(11)T3 on the 3745. Any ideas or help is appreciated.

Mark

3 REPLIES

Re: IP CEF issue

Hi

Can you post the o/p of show ip ospf interface for all ur 3 WAN interfaces here ?

regds

New Member

Re: IP CEF issue

Thanks for the clue!!! I was putting together the output and noticed that the ospf cost for the new WIC was 64 and the pre-existing WIC had a cost of 65. I am not sure why the new WIC had a cost of 64, maybe because it is a single T1 instead of a dual? Anyway, I changed the ospf cost on that interface to match the cost of the existing WIC and it works now. My thanks again for helping me look in the right place.

Mark

Re: IP CEF issue

hi

That was the only point which i thought mite be doing some difference in getting things done..

Anyways good that it solved your quest..

regds

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