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From: dyer@spdcc.COM.UUCP
Newsgroups: comp.dcom.telecom
Subject: bandwidth of LADS (metallic?) circuit
Message-ID: <8705280504.AA05180@spdcc.COM>
Date: Thu, 28-May-87 20:41:19 EDT
Article-I.D.: spdcc.8705280504.AA05180
Posted: Thu May 28 20:41:19 1987
Date-Received: Sat, 30-May-87 05:57:46 EDT
Sender: daemon@ucbvax.BERKELEY.EDU
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Approved: telecom@buit1.bu.edu

I've been running for several months with a LADS circuit between my
house and the university, running at 9600 baud with a pair of Gandalf
LDS 309A short-haul modems.  I'm quite happy with this setup, but I
am wondering how much of the available bandwidth I am using.  If the
leased line is truly just a length of copper which runs from both endpoints
into the central office, and the total length of the wire is probably no more
than a mile, wouldn't there be a chance that the capacity of the line was
greater than 9600 or 19.2kb?   Actually the distance between my house
and the other end is about 2 blocks, but I assume these lines always
must pass through the central office.  Note that this isn't a "voice
grade" line, but something NETel calls "LADS" which presumably means
"Local Area Data Service" or some such.  I think that this is
the same as a metallic line, although it's hopeless to talk to anyone
at the phone company who knows enough about what they're providing.

Are there are bandwidth restrictions imposed on this type of line by
the telco in addition to those imposed by the length?  How would you
recommend measuring the effective capacity of the line?  Is there any
chance of exploiting the residual bandwidth (if there is any at all)
using something other than the LDS309As (or would the expense of such
equipment argue that a DDS line would be cheaper!)  As you can tell,
I'm dreaming of a poor-man's 56kb+ line and am trying to gauge how
much of a pipe dream it is.
---
Steve Dyer
dyer@harvard.harvard.edu
dyer@spdcc.COM aka {ihnp4,harvard,linus,ima,bbn,halleys}!spdcc!dyer