Debug command

The troubleshooting command displays information about Cisco device operations, traffic generated or received, and any error messages. The information is provided in real time until the user disables debugging or the device restarts.

The debugging operation requires a large amount of CPU resources and should not be used frequently in production environments. It is intended to be used as a debugging tool for a short period of time. You can choose to debug only specific events, such as EIGRP information, received ICMP messages, etc.

Consider the following example:

R1 # debug ip icmp
ICMP packet debugging is enabled
R1 #
R1 #
ICMP: echo response sent, src, dst

ICMP: echo response sent, src, dst

In the previous example, you can see that I have enabled debugging only for ICMP events (such as pings). At the output you can see that R1 has responded to the device with the IP address of with two ping response packets.

To disable ICMP event debugging, just type the command with the keyword "no" in front of it:

R1 # no troubleshooting ip icmp
ICMP packet debugging is disabled

To troubleshoot only the RIP messages, we would perform the following command:

R1 # debug ip rip
RIP protocol troubleshooting is enabled
R1 #
R1 # RIP: update v2 was received at on GigabitEthernet0 / 0 to in 2 jumps to in 1 jump
The RIP: v2 update was received at on GigabitEthernet0 / 0 to in 16 jumps to in 16 jumps

You can enable debugging of everything that happens on your device by executing the debug all command (don't use the command on production units because it can produce a large number of results and block the device!)

Remove all command example

To disable this command, type the undebug all command (or all one shortcut).
Debug command Debug command Reviewed by Sirf Tech on January 07, 2019 Rating: 5

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