Last Updated on August 1, 2021 by Admin
You execute the debug ip packet command and find that you receive no output.
Which of the following is the MOST likely reason?
- someone executed the no ip route-cache command
- someone executed the no ip mroute cache command
- someone attached an extended access list to the debug process
- someone executed the ip cef command
When the ip cef command is executed, it enables Cisco Express Forwarding. When CEF is enabled, packets are no longer switched to the processor, so the output shows nothing. You must disable CEF and fast switching on the interface while you are running the debug ip packet command.
Executing the no ip route-cache command would disable fast switching and would enable the gathering of packets rather than disable the operation.
Executing the no ip-mroute cache command would disable fast switching of multicast packets and would enable the gathering of multicast packets.
While it is possible that that an overly restrictive access list could result in NO output, this is only a possibility. On the other hand, it is certain that no output will be produced if the ip cef command was executed. Access lists SHOULD be used in conjunction with the debug ip packet command to reduce the significant amount of information generated and the system resources required to do so.
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