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From: chris@gargoyle.UChicago.EDU (Chris Johnston)
Newsgroups: comp.protocols.tcp-ip
Subject: Re:  How do you break up a B class number?
Message-ID: <719@gargoyle.UChicago.EDU>
Date: Mon, 10-Aug-87 20:15:10 EDT
Article-I.D.: gargoyle.719
Posted: Mon Aug 10 20:15:10 1987
Date-Received: Wed, 12-Aug-87 00:47:33 EDT
References: <8707271742.AA26964@hi>
Reply-To: chris@gargoyle.uchicago.edu.UUCP (Chris Johnston)
Distribution: world
Organization: U of Chicago - Computer Science
Lines: 29

> [paraphrased] we intend to put around 1000 hosts on our backbone.

This has got to be a big lose.  I can think of all kinds of
problems...  And never mind whether or not one segment can support
all that traffic.

Each of the hosts connected to our backbone is a gateway.
Our backbone is implemented with fiber optics rather than coax.

By isolating the major segments of our net behind gateways, we
isolate broken subnets from the rest of the world.  Subnets get
broken in an amazing number of ways.  Electrician/plumber/carpenter
walks near the cable.  Professor unplugs the two thin ethernet cables
from the back of his workstation to rearrange his furniture (no thin
coax in this dept.)  Technician makes a lousy tap and shorts out the
segment.  Technician disconnects the 50 ohm terminator to put an
oscilloscope on the cable (!!!).

The fiber discourages people from making unauthorized taps and is
small enough to be secured out of the way of most harm.

Breaking the net into reasonably small segments is a major debugging
assist.

Of course we are limited to a single protocol (TCP/IP), but since we
want to talk to the rest of the planet we have no choice.  And one
can always pull another pair of fiber and run other protocols on it.

cj