Cisco Support Community
Showing results for 
Search instead for 
Did you mean: 

Welcome to Cisco Support Community. We would love to have your feedback.

For an introduction to the new site, click here. And see here for current known issues.

New Member

filtering debug to syslog

cisco 2651xm router

IOS: c2600-adventerprisek9-mz.124-15.T9.bin

I run a sip trunk on my router and I've been monitoring my sip calls to syslog using 'debug ccsip calls' for a day, the log was going fine and suddenly the log is filling up with hundreds of entries as follows:

Oct  2 18:11:09 19496: .Oct  2 17:11:11.952: %LINK-4-TOOBIG: Interface ATM0/0, Output packet size of 1506 bytes too big,  -Traceback= 0x814F13E4..(lots of numbers).

I see it's to do with the ATM0/0 port which corresponds to the adsl card I use in the router and I recognise  as Vlan1. There's no regular time pattern between entries.

What does this entry actually mean?

Is there a way to configure the debug so it doesn't send these particular messages to the log?

Thanks for any pointers.


Re: filtering debug to syslog

Hello, according to


Interface [chars], Output packet size of [dec] bytes too big

An internal software error occurred.

Recommended Action: Copy the message exactly as it appears on the console or in the  system log.  Research and attempt to resolve the issue using the tools and utilities  provided at  With some messages, these tools and utilities will supply clarifying  information. Search for resolved software issues using the Bug Toolkit  at  If you still require assistance,  open a case with the Technical Assistance Center via the Internet at,  or contact your Cisco technical support  representative and provide the representative with the gathered  information.

Related documents- No specific documents apply to this  error message.

It seems that there is an internal software (IOS) error. From my personal experience it may be that a router reload can fix this error.


New Member

Re: filtering debug to syslog

thanks for your response. Do you mean a reload of the IOS or the running-config?

Re: filtering debug to syslog


I mean reload of your device. Be aware that if this device is productive, local or remote site, if you reload it, you can lose connection to certain services during reload.




Re: filtering debug to syslog

Hello Tony,

Hope you are doing great,

I would like to let you know that traceback it is going to mean that something failed and the router crashed, I would also like to let you know that the problem that you are having it is going to be related with the MTU of the interface.

Can you post your configuration with out the addressing? or private information?

Can you also try this?

interface DialerX
mtu 1492

Int fa 0/0
ip tcp adjust-mss 1452

I hope this will be helpful.


New Member

Re: filtering debug to syslog

hi thanks for your response. Your reference to the mtu makes sense, you'll see from my run.config (attached) I'm using mtu 1430 on the atm0/0. I used this figure because it seemed to give the fastest downloads. I don't use intf0/0 ot intf01, I use ports 1/0 to 1/15 on the router's switch module which is vlan1. I'll hold off making any alterations until you've seen the whole config. Thanks and await yours.