Cisco 3662 PRI T1's "Drop Out of Bundle"

[BaldFromStress]

I am trying to resolve an issue with a Cisco 3662 router (3600 platform) housing 4 active T1 controllers (PRI 2CT1-CSU) and a 16 port ethernet interface. The issue is that the T1 circuits intermittently "drop out" of the configuration bundle then mysteriously come back up, sometimes after weeks or months. They are all administratively up and pass loop-back tests to the CSU. It is not frequent but it happens often enough to create havoc with the network monitors although the users are not affected (at least from their perspective, although bandwidth utilization is reduced). Is this likely to be a configuration issue or is the main board crapping out? Will this kind of thing happen if the onboard memory is pushed too far? Has anyone ever experienced this before?

This is a locally managed device (cannot telnet because of security configurations) and is physically 3 hours from my location, so access to scripts is limited.

Thank you

 

[ISDNman]

You might want to post your question on the Cisco router forum here:

http://www.tek-tips.com/threadminder.cfm?pid=557

From your desciprion the T1s are probably OK. So that leaves hardware or known bugs.

Good Luck!

 

[PeterHurst]

Do whole T1's drop or just individual channels?

If so it could be a clock problem - If the cisco and the T! aren't correctly synced they can drop regularly, how regularly depends on the closeness of the frequency of the clock at each end of the link.

 

[ISDNman]

Good point PeterHurst.

The key word in your post is "regularly". By that you mean "periodically" by which I mean with equal intervals between drops. This is much easier when the interval is small enough you can here is as a regular, periodic, "click" in the audio.

Random clicks would not be due to timing problems, but regular, periodic, clicks generally are.

Best of luck