How to judge whether the router has received or sent specific packets?
Take the Ping test as an example:
Run the debugging ip icmp command to check the processing of the specific application.
Run the debugging ip packet acl 3800 to check whether the IP layer processes the application normally.
Run the debugging physical all interface [interface connected with the peer end] command to check whether the link layer processes the application normally.
Run the acl 3800 command to define the ACL so that only packets that need to view are collected.
rule normal permit ip source 18.104.22.168 0.0.0.0 destination 22.214.171.124 0.0.0.0
rule normal permit ip source 126.96.36.199 0.0.0.0 destination 188.8.131.52 0.0.0.0
rule normal deny ip source any destination any
Generally, if the packets have been sent from the correct interface, which has not received the response packets from the peer equipment, it indicates that the local equipment works normally. In this case, troubleshoot the peer equipment.
If the packets have been received from the correct interface, but the local equipment fails to respond to the peer equipment, it indicates that there is something wrong with the local equipment.
Tip: This method is also applicable to the troubleshooting for the loss of ping packets and ping failure.