logging monitor vs terminal monitor

[whizkidraj]

Hii guys,

I was studying about Syslog and I am stuck here. The commands "logging monitor" and "terminal monitor" are both for vty lines.

What is the difference between these 2 commands. Please do explain with an example i.e. command use-case. Thanks. 

[marce1000]

 - Here's  a good explanation :

       https://networkengineering.stackexchange.com/questions/36603/what-does-monitor-logging-do-in-cisco-ios

 M.

[balaji.bandi]

logging monitor

To enable system message logging to the terminal lines (monitor connections), use the logging monitor command in global configuration mode. To disable logging to terminal lines other than the console line, use the no form of this command.

terminal monitor

To display debug command output and system error messages for the current terminal and session, use the terminal monitor EXEC command.

more information :

https://www.cisco.com/c/en/us/td/docs/routers/access/wireless/software/guide/SysMsgLogging.html

[whizkidraj]

logging monitor command doesn't work in packet tracer, right. I tried.

so "debug ip icmp" with terminal monitor turned on in telnet session, would show the output.

so if logging monitor is tuned on, too, which is disabled by default on vty lines, just like terminal monitor, what would happen?

i.e. both terminal monitor and logging monitor turned on in a telnet session.

the output generated in that telnet session would be shown thanks to terminal monitor command, and in the back end logging monitor what would it be doing at this time..

This is why I asked for some use case. I would have done it, but packet tracer doesn't accept logging monitor command.

If logging monitor 7 is set, then it would also log the debug outputs, right.

So is the difference that logging monitor logs are in the syntax of a syslog syntax i.e.

seq no:time stamp: %facility-severity-MNEMONIC:description

which means logging monitor is a type of syslog command

and terminal monitor is just used for displaying output to debug ip icmp i.e such type of only debug commands.

[Richard Burts · Accepted solution]

While looking at debug output is certainly one use of terminal monitor it is not the only use for terminal monitor. If I were troubleshooting an issue about one of the interfaces which was not working correctly I might use terminal monitor to see log messages indicating when the interface state changed to down, or back to up. Or if I were checking on the operation of an access list where some of the entries included the log parameter, I might use terminal monitor to be able to see what the access list was logging.

The function of terminal monitor is to enable the display of syslog messages on a terminal session (vty session). By default a terminal session does not display syslog messages. Terminal monitor enables the display (and terminal no monitor disables the display). 

The function of logging monitor is to be able to control the severity level of messages displayed to a terminal session. So the severity level of terminal display can be different from the severity level of messages sent to a syslog server, different from the severity level of messages sent to the logging buffer, and different from the severity level of messages sent to the console. 

[whizkidraj]

Thanks, @Richard Burts mate. And sorry I just logged in and saw your reply.

Perfectly explained. Just what I needed. Much appreciated. :-D

[Richard Burts]

You are quite welcome. While the meaning and use of terminal monitor is more straightforward and familiar, the meaning and use of logging monitor is less familiar. Glad that you asked and that our explanations have been helpful. Thank you for marking this question as solved. This will help other participants in the community to identify discussions which have helpful information. This community is an excellent place to ask questions and to learn about networking. I hope to see you continue to be active in the community.

[whizkidraj]

Sure, mate. I definitely keep in mind all the facilities us new generation kids have compared to the old days...so one should definitely use it as much... i.e. research as much in this plethora of knowledge i.e. the internet, and also not be afraid to ask any silly questions to get the basics as clear.. In schools or even in colleges, or other face-to-face mediums such as online-teaching, students don't try to ask much questions. there is always the hesitation...but here on the forums, you can ask as much without being hesitant what others might think...and when you think you can contribute, too, you try to help others as well...as that, too, helps you to learn about something you think you know.

The more you ask or think differently and try to find an answer to that, the more you start discovering new things in itself.