[c-nsp] Debugging T1 Bounces on CT3

[Greg Boehnlein]

On Tue, 5 Apr 2005, Pete Templin wrote:

> Greg Boehnlein wrote:
> > Hello all,
> > 	We have a 7507 w/ RSP4/256M and a VIP-2-50 w/ CT3 card running 
> > rsp-pv-mz.123-11.T3.bin. The CT3 card is plugged into an Adtran MX2800 DS3 
> > mux. The Adtran is used to consolidate DS1 circuits from various carriers 
> 
> Ah, looks fairly familiar to me.  I've got several 7507 RSP4/256M 
> VIP2-50 PA-MC-2T3 combos around my network.  Two of them are connected 
> to MX2820s.  One of them was showing horrendous errors (including the T3 
> controller flapping; a thread here a few weeks ago has me checking 
> 12.0(28)S2, as I'm at 12.0(27)S3 at the moment) on the MC-2T3, but clean 
> as a whistle on the mux.  A cable swap has significantly lowered the 
> errors, but not completely eliminated them.  Next step is to swap to the 
> protect card in the mux, and we're coming up on the window to do that.
> 
> Do you have "sh contr t3 1/0/0 tab", and if so is it clean?

Yes.. and for the DS3 it is clean, except for a 3 second window where at 
the suggestion of Adtran, we switched to the redundant DS3 controller.

I should add that when we initially brought up the Mux, we had Receive 
errors on the CT3 card. After swapping out cables, and a call to Adtran, 
we put a 6 DB attenuator in line and that solved the problem. Apparently, 
the Cisco CT3 receivers are extremely sensitive to overdrive on short 
cable runs, so much so that they sell a ATTEN-KIT-PA= for $150 that 
contains a bunch of attenuators of different DB levels.

In any case, our problem is just the opposite. The DS3 is clean on the CT3 
and we've got errors on the mux.

Adtran has suggested that we do the following:

1. Switch to our redundant controller card (done)
2. Monitor for errors
3. If the problem persists, put a 6db pad on the TX side of the CT3 card.

We'll see what happens..

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