[c-nsp] Strange T3 failure on 7206

[Jay Hennigan]

We got an alarm that a T3 to a customer was down.  PE router showed
interface up, line protocol down.  CE router showed down/down.  Provider
side goes to an Adtran Opti-mux out OC-12 to Verizon, customer end is a
Verizon mux on premise.

Called Vz and they claimed it was CPE, they saw "idle loop" towards our
7206 CE router.  We shut/no-shut the interface and rebooted the 7206, no
joy.  I'm not familiar with the term "idle loop", we were showing
receive LOS and sending RAI.

Customer IT guy came on site and saw CLOS on Verizon mux, alarm light on
7206.  He disconnected the cable and put a coax loop towards the 7206.
Interface came up-looped right away.

Reconnected to Verizon mux and everything came back up nice and happy.
That's what is bugging me.  Circuit has been running fine for months.


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Jay Hennigan - CCIE #7880 - Network Engineering - jay at impulse.net
Impulse Internet Service  -  http://www.impulse.net/
Your local telephone and internet company - 805 884-6323 - WB6RDV