[nsp] Odd T1 problem

From: jlewis@lewis.org
Date: Wed Dec 26 2001 - 14:23:33 EST


I've got an odd T1 problem I've been unable to solve remotely. It's a
BellSouth point to point T1 between 2 locations in the same city. Cisco
1600 and Digital Link Prelude at the Z end, 2620 with WIC-2T and Larscom
Access-T's at the A end. All of a sudden, line protocol (we're using
hdlc) is flapping on both sides. i.e.

Dec 26 19:13:58: %LINEPROTO-5-UPDOWN: Line protocol on Interface
Serial0/3, changed state to down
Dec 26 19:14:00: %LINEPROTO-5-UPDOWN: Line protocol on Interface
Serial0/3, changed state to up
Dec 26 19:14:28: %LINEPROTO-5-UPDOWN: Line protocol on Interface
Serial0/3, changed state to down
Dec 26 19:14:30: %LINEPROTO-5-UPDOWN: Line protocol on Interface
Serial0/3, changed state to up

This site is a couple hundred miles away, and though I don't have anyone
technical there, there is a person able to move wires around. I had them
move the T1 patch cable to another CSU on another WIC-2T port and it kept
doing this...so that eliminates the CSU and WIC port.

I've had bell loop the circuit towards the A side and towards the Z side,
and have been able to run extended pings with various patterns across each
half of the circuit. When they reconnect the A and Z ends in the DACS,
line protocol goes back to flapping. Until it failed, this circuit had
been in use for quite a while, so I don't suspect CSU config issues.

All equipment at each end has been power cycled.

I haven't tried having the remote people replace patch cables, but I
wouldn't think each half of the circuit would have tested ok if there was
a bad cable.

Anyone have any idea what this might be? I really don't want to do it,
but I've run out of ideas other than grabbing enough spare gear to replace
everything at each end and driving up there to replace all the gear and
wiring.

-- 
----------------------------------------------------------------------
 Jon Lewis *jlewis@lewis.org*|  I route
 System Administrator        |  therefore you are
 Atlantic Net                |
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