Path: utzoo!utgpu!water!watmath!clyde!bellcore!rutgers!topaz.rutgers.edu!ron
From: ron@topaz.rutgers.edu (Ron Natalie)
Newsgroups: comp.dcom.lans
Subject: Re: Ethernet bridges above 56Kb
Message-ID: <Jul.25.11.48.50.1988.21899@topaz.rutgers.edu>
Date: 25 Jul 88 15:48:51 GMT
References: <9392@dartvax.Dartmouth.EDU> <116@ernie.NECAM.COM>
Organization: Rutgers Univ., New Brunswick, N.J.
Lines: 24

> A T1 (sometimes called DS1) facility is composed of 24 multiplexed 56
> Kb (called T0 or DS0) circuits.  If your application will use less
> than half of the T1 facility, you might consider a T1 mux and use as
> many T0 circuits out of the 24 that you feel you require for the
> particular application.

Bogus.  A T1 circuit is a serial line of 1,544,000 bits per second.
It is not "composed of" anything.  The frequent telephone use is to
use a channel bank that decomposes it into 24 56K data channels or
even more voice or telegraph channels.  T1 Multiplexors are available
that will carve up the bandwidth to almost any specification.  For
example, our AVANTI Ultramux allows me to reallocate how much bandwidth
I give to each of my interfaces at whim.  Of course, it isn't cheap.

If you are not using the T1 for anything else, you do not need to
waste money on a Multiplexor.  For less money, Digital Link provides
a true T1 CSU/DSU, that allows you to plug a Bridge such as the UB
DLB or the Bridge Communications (Vegalink box) into the T1 line directly.

We use them for Cisco gateways because we find MAC level bridges do
not provide sufficient fault isolation in a network as diverse as
ours.

-Ron