Monday, January 7, 2019

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 10.0.0.2, dst 10.0.0.1

ICMP: echo response sent, src 10.0.0.2, dst 10.0.0.1

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 10.0.0.1 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 10.0.0.1 on GigabitEthernet0 / 0
172.16.0.0-16 to 0.0.0.0 in 2 jumps
192.168.5.0/24 to 0.0.0.0 in 1 jump
The RIP: v2 update was received at 10.0.0.1 on GigabitEthernet0 / 0
172.16.0.0-16 to 0.0.0.0 in 16 jumps
192.168.5.0/24 to 0.0.0.0 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).

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