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ISR 4321 "debug ip icmp" command not capture icmp packet

Hello, when trying to enable  icmp debug by using command "debug IP icmp" in ISR 4321 router, it doesn't capture received icmp packets. But if i send icmp packet to others from the router, the router capture icmp packet normally. Does this situation be normal?


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VIP Expert

can you post the put of the debug to look what you seeing.


in general, that is natural since it processed by FAST or CEF switching.


iif you use the command no ip route-cache or no ip route-cache cep, you can get what you looking.


here is some reference :


you may get more details if you issue  "debug ip packets detail"  (this is more CPU intensive - be careful on the production network.)


*** Rate All Helpful Responses ***

Does "debug ip icmp" command only debug data processed by CPU likewise "debug IP packet" ? 

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