[c-nsp] Cisco Fixed 75 Ohm Attenuators

[Eric Kagan]

I read through the previous thread a few months back on this and I am having
a similar problem:
https://puck.nether.net/pipermail/cisco-nsp/2005-October/025336.html

I would like to run this scenario by you to see if it seems I am running in
to an attenuator issue or bad card.  I have a lab setup with the following:

Cisco 7206VXR w/ PA-T3 <->  Adtran Opti 6100 DS3 mapped to OC3 <---> Adtran
Opti 6100 DS3 mapped to OC3 <-> Cisco 7206VXR w/ PA-2T3

If I put the Cisco DS3 back to back I get no errors (10,000, 1,500 or 10,000
byte pings) 100% success, no loss

If I pass the DS3's over the Adtran Mux, I usually lose about 4 or 5 packets
out of 10,000.  One of the cards (PA-T3) will then have a few input errors
(5 or 6) and a few LCV (5 or 6).  The other card is clean.  I have swapped
the cables, routers, etc and it always follows the PA-T3.

I spoke to Adtran Tech Support and he went through all settings, hard loops,
etc and said it all looks clean and he mentioned the attenuator issue so I
started doing some digging.  We confirmed the Adtran is okay back to back
with Fiber attenuators and there are no errors on the OC3 or DS3.

So, is this the attenuator issue ?  Is the Rx too strong on just that card ?
Or could the card be bad.  Unfortunately, I don't have another PA-T3 handy.

I tried longer cables, changing the cablelength to shorter than 10 (default)
and that helped.  (I was getting a few hundred LCV before this). I have
changed clock settings, etc, but I can't ever make 100% success across the
DS3's.  Is there anything else I can do / check to confirm or determine the
problem or should I try the attenuator route ?

Thank you
Eric