Logging Console Command on CISCO Router/Switch

Command

Logging Console

Use

This is a handy command that stores log messages so they can be reviewed later. This is a default command.
It is especially useful when you are telneting between multiple routers as you would normally miss the console or debug messages on the router your not connected to.
Each logging level also enables the logging level below it, so logging console 7 or logging console debug will enable all log messages.

Syntax

Router(config)#logging console <level>

Optional Switches

<0-7>
<4096-2147483647>
alerts
critical
debugging
emergencies
errors
filtered
informational
notifications
warnings
xml
Logging severity level
Logging buffer size
Immediate action needed (severity=1)
Critical conditions (severity=2)
Debugging messages (severity=7)
System is unusable (severity=0)
Error conditions (severity=3)
Enable filtered logging
Informational messages (severity=6)
Normal but significant conditions (severity=5)
Warning conditions (severity=4)
Enable logging in XML to XML logging buffer

Example

In this example, we will enable logging console debug.

R2(config)#logging console debug

Now we will telnet from R1 to R2 and check the debug output.

R2(config)#
*Mar 1 02:44:47.503: IP: tableid=0, s=2.2.2.2 (local), d=10.1.1.1 (FastEthernet0/0), routed via FIB
*Mar 1 02:44:47.507: IP: s=2.2.2.2 (local), d=10.1.1.1 (FastEthernet0/0), len 70, sending
*Mar 1 02:44:47.671: IP: tableid=0, s=10.1.1.1 (FastEthernet0/0), d=2.2.2.2 (Loopback0), routed via RIB
*Mar 1 02:44:47.675: IP: s=10.1.1.1 (FastEthernet0/0), d=2.2.2.2, len 40, rcvd 4
R2(config)#
*Mar 1 02:44:48.807: IP: s=10.2.2.3 (FastEthernet1/0), d=224.0.0.5, len 80, rcvd 0
R2(config)#
*Mar 1 02:44:50.339: IP: s=10.1.1.1 (FastEthernet0/0), d=224.0.0.10, len 60, rcvd 2
*Mar 1 02:44:50.467: IP: s=10.1.1.2 (local), d=224.0.0.10 (FastEthernet0/0), len 60, sending broad/multicast
*Mar 1 02:44:50.995: IP: s=10.2.2.2 (local), d=224.0.0.5 (FastEthernet1/0), len 80, sending broad/multicast
R2(config)#
*Mar 1 02:44:55.171: IP: s=10.1.1.1 (FastEthernet0/0), d=224.0.0.10, len 60, rcvd 2
*Mar 1 02:44:55.259: IP: s=10.1.1.2 (local), d=224.0.0.10 (FastEthernet0/0), len 60, sending broad/multicast
R2(config)#
*Mar 1 02:44:57.531: IP: s=10.1.1.1 (FastEthernet0/0), d=224.0.0.9, len 92, rcvd 2
R2(config)#
*Mar 1 02:44:58.791: IP: s=10.2.2.3 (FastEthernet1/0), d=224.0.0.5, len 80, rcvd 0
*Mar 1 02:44:59.459: IP: s=10.1.1.1 (FastEthernet0/0), d=224.0.0.10, len 60, rcvd 2
R2(config)#

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