Wednesday, August 4, 2010

Debug Filtering

Hi Guys,

Sorry about the long time between posts, I only just returned from my holiday to Las Vegas and New York (which was great fun :))

Now onto the important stuff. In my own CCIE Voice studies I am now preparing for the lab proper, meaning I believe I have covered the majority of the topics and I am now actively taking practice labs and should be heading to IP Experts Bootcamp very soon.

One of the things I am doing to prepare for this is troubleshooting work. Troubleshooting is going to make up a big portion of the lab according to Cisco themselves, so anything you can do for yourself in this section is going to help big time.

So with that in mind, I started reading through this document on

I found a very interesting section that talked about voice call debug filtering. What this allows you to do is filter what debug output you want to see based on particular settings. How incredibly useful! I cannot tell you how often I have wanted a particular SIP message to be displayed, only to have to try and wade through SIP notify messages, registration messages and other garbage before I could get to the debug message I actually cared about.

Below you will see an example of how it is done, in my example we are simply doing a debug voip dialpeer inout but we only want to capture calls coming from 5002 and not 5007

Lets take a look:

First create your debug filter list
call filter match-list 10 voice
incoming calling-number 5002

you can match on a whole bunch of conditions of course, and a simple press of the ? will show you the myraid of options you have here.

Next, you need to apply this filter:

PeterCCIE18371#debug condition match-list ?
<1-16> tag number

obviously enter whichever tag number we created earlier.

then run your debug command
PeterCCIE18371#debug voip dialpeer inout

once this is done, you can verify with:

PeterCCIE18371#show debug

debug voip dialpeer inout is ON (filter is ON)

and you can see your criteria with:

PeterCCIE18371#show call filter match-list

call filter match-list 10 voice
incoming calling-number 5002
debug condition match-list is set to EXACT_MATCH

all in all an incredibly useful tool. Now be careful to make SURE you turn off this filter when your done looking, because as far as i can tell simply doing an undebug all does NOT remove the filter condition. So keep this in mind!!

Until next time!


1 comment:

  1. I did not know about "debug voip dialpeer inout" option until I found this article. I think it's one of the Cisco commands that are not well documented.