Inter-connectivity between routers through a catalyst

[eddie.lindsay]

Hi,

I have 2 7206VXRs inter-connected through a catalyst 3500XL switch using VLAN 1. I am running CEF on the 7206s but in order to get stable inter-connectivity between the routers I have to disable cef switching on the fastethernet interface attached to the cat switch (no ip route-cache). If I leave route-cache on the connectivity is intermittent and my OSPF and MPLS LDP adjacencies break.

I am running 12.2 IOS on the routers and 12.1(5) on the cat switch.

Anyone seen this before?

Thanks

[hatem.kevin]

There are known IOS bugs associated with CEF, but I have only seen and experienced them on earlier code than what you are running. 12.2 should have the known CEF bugs eliminated from it. I doubt the code on the 3500 is the culprit; the 12.1(5) code is stable on the 3500 and CEF is l3 dependant on the routing table and FIB, so it's only l2 between the 35 and 72. Try to trim the config on the 35 and eliminate the VLAN interface and its IP; or even directly connect the 7200 with a crossover and see if CEF works....If not, the problem could still be with the IOS.

[jevansau99]

We had a similar problem with a 7500 using 12.2(3) and had to issue the "no ip route-cache cef" command to get things running. so i don't know if 12.2 has all the cef bugs fixed.