Path: utzoo!attcan!uunet!husc6!bu-cs!kwe
From: kwe@bu-cs.BU.EDU (kwe@bu-it.bu.edu (Kent W. England))
Newsgroups: comp.dcom.lans
Subject: Re: Ethernet bridges and T1-izers
Message-ID: <24058@bu-cs.BU.EDU>
Date: 26 Jul 88 16:39:09 GMT
References: <9392@dartvax.Dartmouth.EDU> <Jul.22.20.57.24.1988.24248@athos.rutgers.edu>
Reply-To: kwe@buit13.bu.edu (Kent England)
Followup-To: comp.dcom.lans
Organization: Boston Univ. Information Tech. Dept.
Lines: 22

In article <Jul.22.20.57.24.1988.24248@athos.rutgers.edu>
hedrick@athos.rutgers.edu (Charles Hedrick) writes:

>To use a whole T1 circuit with a bridge or router, you
>have to use a box that takes a generic 1.5 Mbps signal and puts it
>into the funny T1 format.  I call such a box a T1-izer.  
[...]
>In general the bridges and routers don't know and
>don't care exactly how fast a line is.  They just lock onto the clock
>that comes from the T1-izer of multiplexer.  

	That raises some interesting questions.  Depending how "smart"
the T1-izer is in doing the required bit stuffing, it might present a
higher or lower clock rate to the bridge.  What differences are there
among T1-izers and do vendors advertise what the true clock rate to
the interface is?

	Are any T1-izers capable of data compression and if so what is
the expected gain?  Could we get effective throughputs of 2Mbps over a
T1 circuit? Or is this capability best left outboard of a T1-izer?

	Kent England, Boston University