🚀 go-pugleaf

In article <210@pwcs.UUCP>, dennisg@pwcs.UUCP (Dennis Grittner) writes:
> In article <436@svax.cs.cornell.edu> jqj@systems.cs.cornell.edu (J Q Johnson) writes:
> >I'm planning Ethernet wiring for a new building (about 150 stations).
> >I'd been planning a traditional scheme with thick backbone+xcver in
> >hallway raceways and drops into each office, similar to my existing
> >offices.  However, I am investigating using thin Ethernet instead.
> >
> I would like responses on this to be posted to the net. I have
> similar questions about thin ethernet and mixing thick and think
> as well as the specific devices for doing this AND is any/all of
> this a good idea.
 
I've installed a so called thin ethernet here in 150+ workstation environment.
All the workstations are HP 9000s running Unix. In addition there are
several mainframes connected to this same network.
 
Thin ethernet was helpful for us because we have an open office environment
which uses cubicles instead of walls. We just drop the cable from office
to office, and make sure there is a BNC "T" connector in each office. 
Although the thin segment can be up to 185meters and 30 connections I try
to keep the length and number to less than 100m and 10 connections. This
way I'm flexible for expansion or change. I use a multi-port repeater
built by HP called the HP 28645A which connects 4 thins to single thick
cable. It has half the delay of a standard repeater which means that 
if you had no other repeaters on the net you could cascade these guys 
4 deep. Although I can't say for sure unless DEC really screwed up 
their multi-port repeater should have similar characteristics. 
 
What I have found in running this thin stuff is that buying preconnected
cable is a major win. Also, trying to put a wall plate in each office
is not worth the effort. I figure how much cable it takes to go from
office to office and buy a bunch of cables for that length. Then each
office essentially has two cables coming in connected by a T. If someone
decides to add another host(s) in that office I just insert as much cable
and Ts as is necessary. BTW: There is no minimum distance spec necessary to 
maintain in thin LAN (ie: you can place connections as close together as
you want).

The multi-port repeaters connect to a backbone(s) of thick cable which
runs between the floors of this building and finally ends in the computer
room where it ties into the mainframes.

One advantage of the multi-port repeaters is that they provide electrical
isolation to the remainder of the network. If any individual thin segement
gets unterminated or damaged for some reason the repeater isolates that 
segment. If you need to change a particular part of the network you
don't run the risk of bothering all the users on the net by making a
bad tap. Besides, this RG-58 stuff is a lot easier to pull than a long
tranceiver cable or the yellow cable.
 
Hope this helps. I can tell you about how we are using multiple thick
backbones, ethernet patch panels and IP gateways in our environment 
if you are interested.
 
- Robert ( michaels@hplabs )
 
DISCLAIMER: Please understand that these are my opinions and do not
	    necessarily state official HP policy.