Subject: RE: (usr-tc) PRI service message docs

From: Brian Becker <[email-masked]>
Date: Thu, 29 Mar 2001 14:26:37 +0000

Hi Mike,
We've seen something similar to your description several times with different telcos (not pri though...channelized T1s) and
requested the tester to submit a ticket to switch to a spare circuit. Every time we've been told we would have to pay for rolling
the trucks and we agreed...knowing that if it fixed the problem then they couldn't charge us. Never paid yet!

Brian Becker
President, Poplar Bluff Internet, Inc. (www.semo.net)
Home of TotallyFabricated.com Software:
  Total Scrutinizer (www.TotalScrutinizer.com) - Tech Support Just Got Easier!
  WebGabber (www.WebGabber.com) - html-based Chat Software

-----Original Message-----
From: [email-masked]
[mailto:[email-masked]]On Behalf Of Mike Andrews
Sent: Thursday, March 29, 2001 12:57 AM
To: [email-masked]
Subject: (usr-tc) PRI service message docs

Hey folks...  Anyone have any good low-level docs on PRI service messages?
Anyone know q.931 and q.921 really well?

I'm trying to track down a really bizarre PRI problem I'm having with the
telco in one city.  The HiPer DSP software (2.1.9) doesn't appear to give
you much in the way of D-channel debugging at all... except for the
"trc debug 25 2" command that gives a hex dump of the packets on the
console.

So, I'm writing a program to take that hex dump and turn it into something
readable.  (Hey, it's a good excuse to finally learn about q.931, too.)
It mostly works, except for service messages -- it doesn't really grok
them correctly.  In particular they come in with weird protocol
discriminator numbers like 0x03 and 0x43 instead of the usual 0x08.
Unfortunately, Google is not helping me as much as it usually does here.

The specific PRI problem is calls aren't hitting my PRI's; it takes about
10 calls and starts to fast-busy or dead-air... *sometimes* calls will
roll over to the next PRI, sometimes not.  Every so often the switch sends
a series of service messages with protocol discriminator 0x43, with a list
of B-channels -- probably the switch thinks my lines are busied out and it
wants me to restore them.  The DSP does not acknowledge these packets.
I've been able to fix this condition before by rebooting the DSP's, but
that doesn't exactly tell me why it's happening in the first place....
One theory is that maybe the telco is set to NI-2 instead of DMS-100
Custom... of course they say it's set to DMS anyway...

Mike Andrews * [email-masked] * [email-masked] * http://www.bit0.com
VP, sysadmin, & network guy, Digital Crescent Inc, Frankfort KY
Internet access for Frankfort, Lexington, Louisville and surrounding counties
www.fark.com: If it's not news, it's Fark.  (Or something like that.)

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