Path: utzoo!attcan!uunet!pyrdc!netsys!vector!nobody
From: goldstein%delni.DEC@decwrl.dec.com (Fred R. Goldstein dtn226-7388)
Newsgroups: comp.dcom.telecom
Subject: Re: DMS-100 problem
Message-ID: <telecom-v08i0175m02@vector.UUCP>
Date: 9 Nov 88 12:07:00 GMT
Sender: chip@vector.UUCP
Lines: 18
Approved: telecom-request@vector.uucp
X-Submissions-To: telecom@bu-cs.bu.edu (TELECOM Digest Coordinator)
X-Administrivia-To: telecom-request@vector.uucp (USENET Telecom Moderator)
X-TELECOM-Digest: volume 8, issue 175, message 2

In issue 174, someone at AT&T asked about a synchronization problem
with the DMS-100.  To the best of my knowledge, this is not a DMS-100
problem per se, as similar problems occur in other exchanges where
T1 carrier is in use between switches (many or most).  The problem
is that every line is supposed to be synchronized to a master clock
in a heirarchy.  The DMS is supposed to be slaved to one line (with
another as backup), and all of the incoming T1 lines are also
supposed to be slaved, eventually, from the master.  (There's a
multi-strata set of rules for this.)

Since you can't _hear_ slips, telco people get sloppy and sometimes
don't set up things right.  It's possible, then, that one of the T1
lines is not synchronized to the switch.  This "plesiochronous"
operation ($10 word for "just out of sync") usually results in a
very regular (every n seconds) error on modems.  You have to pester
the telco to get it fixed; it matter what exchange the call is to/from,
since it's usually on the interexchange trunks.
      fred