cef on c7200/2600

[mbhat]

How are ICMP packets processed on these platforms ? Are ICMP packets by default cef switched on a 7200, or is it that the first packet is process switched and the following set of icmp packets to the same destination are cef ?

And does it work the same way for a C2600 ?both are using the IOS 12.07(T).

[deilert]

If there is an entry in the Cef table they are CEF switched . I have proven this by using the ping with record option. we have had stuck entries in the CEF table where pings would time out. If the same address was pinged using the reord option the pings would be successful. When you use the record option with ping the packets are process switched .

Hope this helps

[mbhat]

Hi Dave,

Thanks for you explanation.

Could you please let me know how you simulated and verified the same, i would have to present the same to my cu.

regards,

mahe

[deilert]

Unfortunately you can not simulate a entry that is 'stuck' in the CEF table. It happens when you have a legitimate route to a network pointing out a specific interface but the CEF table has an entry that tells the router to send the packet out another interface . This will usually happen when you have an interface that was flapping , then became stable the Cef entry and entry in the routing table changed when the flapping was occurring once the link stabilizeed the routing table will point out that interface but the CEF table never updates.