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Re: Common operational misconceptions
From: Michael Sinatra <michael () rancid berkeley edu>
Date: Thu, 16 Feb 2012 11:10:45 -0800

On 02/16/12 05:17, Ray Soucy wrote:
I've found starting off with some history on Ethernet (Maine loves Bob
Metcalfe) becomes a very solid base for understanding; how "Ethernet"
today is very different; starting with hubs, bridges, collisions, and
those problems, then introducing modern switching, VLANs, broadcast
domain's etc.

There was an old cruddy 1950s building on the UCB campus called Stanley Hall. (Now there's a new, nice, modern building on the UCB campus called Stanley Hall in place of the old one.) The old building had both UCB net and Lawrence Berkeley Lab (LBNL) net running through it. The LBNL net was fed from fiber using a 10base-FL-to-AUI repeater. The AUI connected into the coax spine.

The cool thing is that the coax spine was provisioned exactly as you would expect in an old ethernet textbook. The spine ran through the hallway (usually just tied to a pipe, but sometimes with a J-hook) and every 1.5 meters, there was a vampire tap and (usually) a transceiver with an AUI cable connected to it that went into an office and dropped down through the ceiling.

Amazingly, the UCB network was somewhat more modern. There were DEC Delni MPTs (or "AUI hubs") coming off the UCB coax. There were even some 10base-T hubs and concentrators that fed offices that had newer cat-3 or even cat-5 wiring.

It was great to take students on tours through this operational museum. (Well, the LBNL net was sort of operational. It would just stop working for minutes on end and then come back mysteriously.) You could basically see the first 10-15 years of the evolution of ethernet, and it was installed and working.

The new Stanley is plumbed to the gills with cat-5e, gigabit switches, and vlans all over the place. A modern LAN, yes, but no sense of history.


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