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Can ping, but no traceroute? Any suggestions on what to look for?

I have a problem on a network of ours. We have a 6509/MSFC2 that is connected to a switch (3550-12G) and in turn connected to a router (7206). The connection between the 6509 and the 3550, and the connection between the 3550 and the 7206, is a access port on VLAN 62. There is also a trunk connection between the 6509 and 3508 which contains VLANs 1-10. The default gateway for the 3508 is the 6509. EIGRP routing is being used on all equipment. The 3550 is not configured to do any routing.

Any cisco equipment on the network can ping the 7206, but not traceroute to it (ends at the MSFC). The MSFC correctly shows the route, which is learned via EIGRP, to the 7206 as going out VLAN62.

The 7206 can ping any equipment on the network, but it cannot traceroute to the 6509. I can traceroute through the 6509 to any piece of equipment on the network from the 7206, and it shows up on the path, but I can't terminate a traceroute to the 6509.

Any connection that comes in via the serial interface on the 7206 can terminate a traceroute on it.

We have noticed that we can traceroute to the box from a windows machine, which means an ICMP traceroute is working, while a UDP traceroute isn't. However, turning on UDP packet debugging on the 7206 shows that the UDP traceroute packets are reaching the router.

Any suggestions on where to go from here to figure this out? Can anyone think of anything that might cause this that we might not have checked already?

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Re: Can ping, but no traceroute? Any suggestions on what to look

I've seen some strange stuff on Cat 6500's when the IP CEF forwarding table gets screwy. In our problem, we had some parts of a subnet could route to places, others could not. Try turning off IP CEF on the 6509 and see if it behaves differently.

Re: Can ping, but no traceroute? Any suggestions on what to look

Hmm.. Can you turn off CEF on a MSFC2? The documentation I find on it and it tells me I can't turn it off on this platform.

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