Path: utzoo!utgpu!water!watmath!clyde!att!pacbell!lll-tis!helios.ee.lbl.gov!nosc!ucsd!ucsdhub!hp-sdd!hplabs!hpda!hp-sde!wunder
From: wunder@hp-sde.SDE.HP.COM (Walter Underwood)
Newsgroups: comp.dcom.lans
Subject: Re: Ethernet bridges above 56Kb
Message-ID: <470010@hp-sde.SDE.HP.COM>
Date: 21 Jul 88 18:07:10 GMT
References: <9392@dartvax.Dartmouth.EDU>
Organization: HP Software Dev Environments - Palo Alto, CA
Lines: 21


   All the bridges that I have seen either use an entire T1 circuit, or
   use only 56Kb of it.  Does anyone know of one which can be configured
   for data rates between these limits?

T1 equipment almost always uses an external clock.  Good T1 equipment
still works when you change the clock rate, so actually running at
.75122 Mbits shouldn't be a problem.

2:1 muxes are pretty common for 56Kbit lines, and probably exist
for T1.  Some of the muxes are also compression boxes, so you might
look around for compression equipment that takes two or more
channels in and puts out a T1.

Some compression boxes do flow control by varying the clock.  If
they want the source to slow down, they slow it down.  It is a good
idea to test equipment to see if it can handle that sort of thing.
At HP, I believe that we use cisco boxes through Datamiser
(Datamizer?) compression boxes that use the clock for flow control.

wunder