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6506 w/Sup2&MSFC2 Possible CEF Problems

We're trying to get a 6506 with a Supervisor2/MSFC2 and an ATM OC-12 module going to replace an aging Alcatel(Xylan) Router. The ATM module brings in various ATM ELANs which are mapped to VLANs on the 6506 which the MSFC2 routes between. When the 6506 is in the production network the ATM connections come up fine and we get routes from OSPF. Things look ok, some however TCP related sessions hang. We've seen interruptions with SSH, HTTP, and SMTP. I've checked the CEF entry tables and everything looks OK. These problems promptly disapear when the Alcatel router is brought back into the network. It seems to be a Layer 4 problem, a host where SSH hangs, pings and telnet will work.

Does anyone have any hints for tracking down CEF problems or any other Multilayer Switching problems on the 6506? I know its a weird one but I'd like to get some insight into the problem before our eval. period on the switch expires.


CatOS version 6.3(3)

MSFC2 IOS version 12.1(7a)E

WS-X6101-OC12-MMF IOS version 12.1(8a)E

Any help would be greatly appreciated.

-- Joe Patry


Re: 6506 w/Sup2&MSFC2 Possible CEF Problems

Often times complex troubleshooting issues are best addressed in an interactive trouble-shooting session with one of our trained technical assistance engineers. While other forum users may be able to help, it’s often difficult to do so for this type of issue.

To utilize the resources at our Technical Assistance Center, please visit and to open a case with one of our TAC engineers, visit

If anyone else in the forum has some advice, please reply to this thread.

Thank you for posting.