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From: hedrick@TOPAZ.RUTGERS.EDU (Charles Hedrick)
Newsgroups: comp.protocols.tcp-ip
Subject: Re: DSU/CSU units
Message-ID: <8709242204.AA10494@topaz.rutgers.edu>
Date: Thu, 24-Sep-87 18:04:52 EDT
Article-I.D.: topaz.8709242204.AA10494
Posted: Thu Sep 24 18:04:52 1987
Date-Received: Sat, 26-Sep-87 18:02:39 EDT
Sender: daemon@ucbvax.BERKELEY.EDU
Organization: The ARPA Internet
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8ZBS generates bipolar violations of a specific kind.  Some
telco equipment allows it and some does not.  For single-channel
T1 (i.e. two IP gateways that want the whole bandwidth of a 
T1 connecting them), we have used a gadget from Digilink
that I call a T1-izer.  It takes a vanilla synchronous signal,
and supplies everything that is needed to pass it through T1.
There are a number of switches that control the encoding.
You can select 8ZBS, if your telco can hack that, or a more
convservative encoding if they can't.  (There is of course a
slight benefit in terms of line speed if you use 8ZBS.)
THis also has a DSU/CSU builtin.  (However we more typically
use Avanti equipment, because we need to multiplex several
channels on one T1 line.)