Path: utzoo!attcan!utgpu!jarvis.csri.toronto.edu!mailrus!accuvax.nwu.edu!nucsrl!telecom-request
From: westmark!dave@uunet.uu.net (Dave Levenson)
Newsgroups: comp.dcom.telecom
Subject: Re: Slick 96?
Message-ID: <2051@accuvax.nwu.edu>
Date: 12 Dec 89 00:53:17 GMT
Sender: news@accuvax.nwu.edu
Organization: Westmark, Inc., Warren, NJ, USA
Lines: 52
Approved: Telecom@eecs.nwu.edu
X-Submissions-To: telecom@eecs.nwu.edu
X-Administrivia-To: telecom-request@eecs.nwu.edu
X-Telecom-Digest: Volume 9, Issue 567, message 6 of 6


In article <2018@accuvax.nwu.edu>, djb@loligo.cc.fsu.edu (Dave Brightbill) 
writes:

> My rural community is served by Centel.  A few years ago, we upgraded
> our home service from a 4-party line to a private line.  Because of a
> lack of available pairs, we had to wait for a line.  The telco solved
> the problem by installing some sort of magic box on a post in our
> community.  All of our lines have been wired back to it.  The
> installer called it a "slick-96" box, and from her description, I
> would guess that it is some sort of mux.  My guess is that the "96"
> refers to 9600 baud.  So is this a digital mux?  Can it do any tricks?

We, too, have service from the local telco via SLC-96 (which is
Subscriber Loop Carrier, 96 channels per T-1 span).  This system uses
digital multiplexing and local switching to concentrate a large number
of subscribers on a small number of 1.55 Mbit digital loops to the CO.
It regenerates battery feed, ringing, loop current interrupts, and
anything else needed to support your local Tip and Ring telephone
sets.

A group of T-1 links to the CO (or fiber, in some installations)
provide the physical circuits.  Each T-1 link supports 24 derived
voice circuits, using digital multiplexing.  The actual ratio of
supported subscribers to available derived circuits is engineered to
provide an acceptable blocking probability, based upon the traffic
generated by the subscribers served.  When you're using a CO line, you
get switched on to one of the available derived channels.  When you're
not, no channel is assigned.  It's fast enough that you'd never notice
it, except for the minute probability that no channel will be
available when you want service.  In that case, you'd experience a
wait for dial-tone, or a party calling you would experience a fast
busy (I think).

We have run voice and data through that mux for several years, and
have never experienced data integrity or blocking problems.  The
transmission quality is noticably better than it was when we had
loaded-loop metalic circuits, a few years ago.

When it was first installed, the remote terminal was buried in a vault
under a man-hole a few blocks from here.  There was a lot of
excavation, and lots of noise while it was under construction.  This
moved a few of our neighbors to ask the town zoning board to deny
permission to the Telco for use of their easement in this manner.  I
don't know how the politics finally were resolved, but the mux was cut
back in about 1986 or so, and probably bothers nobody today!


Dave Levenson                Voice: (201) 647 0900
Westmark, Inc.               Internet: dave@westmark.uu.net
Warren, NJ, USA              UUCP: {uunet | rutgers | att}!westmark!dave
[The Man in the Mooney]      AT&T Mail: !westmark!dave