Got a question for the Lucent RABU engineers on the list. We've got quite
a few PM3's in production and all have worked marvelously. Installation
has been a snap, and configuration takes all of about 5 minutes. Until
this last week that is. Built a new POP, and installed the first PM3.
Everything looked fine, plugged in the PRI and noticed a lot of BiPolar
and CRC violations on the line. I had the CLEC providing the PRI, optioned
for B8ZS/ESF u-law, run loopbacks from the switch all the way to the
smartjack. These ran clean. Looped up the PM3, and got errors on the loop.
Distance from the smart jack to the PM3 is 15 feet. Tried three cables,
two other PM3's, all to no avail. Still seeing errors on the PRI and the
D-Channel bouncing up and down. Switch is a DMS-100. We plugged a spare
Adtran CSU into the PRI, and looped clean to that. Plugged the PRI back
into the PM3, and saw errors on the loop again.
This went on for about two days of replacing the PM3's, replacing the
cables, replacing the smartjack, etc. Finally, we started playing with
the dB level on the line. It was running at about +1 dB according to the
test equipment we had on hand. We tried lowering that until we got it to
-0.3 dB at which point the PM3 looped clean, and we saw no errors being
reported on the line. It's now run clean for about 24 hours.
My question is, is a higher receive level, say +1 dB, known to cause CRC
and BiPolar violations? It falls in the range reported by the PM3 as
+2 dB to -7.5 dB, yet, running at +1 dB caused the problems, and lowering
it to -0.3 dB caused the problems to dissappear. What is the range of
receive levels which are acceptable to the PM3? I had assumed it would
be +2 to -7.5, but that apparently isn't quite the case.
Am I just seeing someting weird or do I need to make sure the receive
level is not just in the +2 to -7.5 range, but in a smaller acceptable
range?
Oh, the ComOS is 3.7.2c3.
-Chris
--
\\\|||/// \ Chris Parker: Systems Administration and Development
\ ~ ~ / \ cparker@starnetusa.net \ cparker@megapop.net
| @ @ | \ www.starnetusa.net \ www.megapop.net
oOo---(_)---oOo--\------------------------------------------------------
\ Without C we would have 'obol', 'basi', and 'pasal'
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