[c-nsp] CT3IP (aka PA-MC-4T1) problems

[joe mcguckin]

I have a a CT3IP with a PacBell/SBC/ATT Channelized Ds3 connected.  
The line has worked great for years. Now, all of a sudden, the Ds3  
will bounce for hours, then
will come back. If I physically unplug the DS3 cables, that will  
restore the connection also.

I'm pretty sure this is a carrier problem - I've tried multiple I/O  
cards - all with the same result.

One thing we're seeing is hdlc error messages:

Apr 12 11:23:37 gw.sfo 122918: Apr 12 11:23:37: Illegal HDLC serial  
type code 69, PC=0x400D6FF8
Apr 12 11:23:37 gw.sfo 122919:
Apr 12 11:23:37 gw.sfo 122920: Apr 12 11:23:37 pdt: %CONTROLLER-5- 
UPDOWN: Controller T3 6/0/0, changed state to down


What are the conditions that would cause the DS3 controller to go  
down? Is there any more debug info we can gather?

Any ideas?

Joe