Path: utzoo!utgpu!news-server.csri.toronto.edu!bonnie.concordia.ca!uunet!math.fu-berlin.de!fub!einoed!bitcave!cosheff
From: cosheff@bitcave.in-berlin.de (Charles O. Shefflette)
Newsgroups: comp.dcom.lans
Subject: Re: how to connect thin wire segements to thick wire backbone
Message-ID: <1991May18.231445.18574@bitcave.in-berlin.de>
Date: 18 May 91 23:14:45 GMT
References: <1991May13.170657.4786@zoo.toronto.edu> <3021@kirk.nmg.bu.oz.au> <1991May15.195831.16169@nmt.edu>
Organization: BitCave BBS, Berlin, FRG
Lines: 62

rmilner@zia.aoc.nrao.edu (Ruth Milner) writes:

>In article <3021@kirk.nmg.bu.oz.au> bambi@kirk.nmg.bu.oz.au (David J. Hughes) writes:
>>From article <1991May13.170657.4786@zoo.toronto.edu>, by henry@zoo.toronto.edu (Henry Spencer):
>>> The only way to hook cables
>>> together at other than their ends is with a repeater of some flavor.
>>
>>Correct yet not correct.  
>>The set-up we use here is ...........
>[ diagram deleted ]
>>
>>The Star configuration is maintained by a Multi-Port repeater 
>                                           ^^^^^^^^^^^^^^^^^^^
>How does this differ from what Henry said?

>The point is, you can't hook the cables together without a box somewhere in
>between. Whether you have one box for each thinwire segment, or one for many,
>is irrelevant. You still need something with some intelligence to join them.
>Multi-port repeaters have that intelligence: they are proper repeaters, and
>most of the ones available on the market also do fault isolation on the thin
>segments, which is quite useful.

Well, that isn't exactly true, either.  According to the 3COM and to the
Cabletron manuals we have, the only thing you really have to do to
connect thin- and thick-wire ethernet together is to use the appropriate
adapter connector between them.

You do have to be certain that you don't exceed the cable length 
restrictions for the thin-wire when you make the connection, but other 
than that you don't really have any problems with them.  The transcievers 
are identical except for the actual tap onto the net, so the ethernet 
cards, etc. won't even know or care what they are physically connected to.

In our case we have just this configuration, a thickwire system with
some thinwire connected to it with type N to BNC adapters.  In the system
we have about 50 workstations connected and experience no problems with
the network except for the occasional failed transciever.

Our network map looks something like this:

#=======#=============#    #==============#========#========#=====
|       |             |    |              |        |        |
Server  |             Fiber             Repeater Repeater  Repeater
     Repeater                             |        |        |
        |                                 |        |        |
========#===-------                    ===#==    ==#===   ==#===

... etc...

where:
 ===  is thick ethernet
 ---  is thin ethernet
 #    is an ethernet tap

This doesn't actually depict our real layout, it's lots more complex
than that, but you should get the general idea.

-- 
=============================================================================
Chuck Shefflette                    cosheff@bitcave.in-berlin.de
System Engineer                     (cosheff@netmbx.in-berlin.de)
ManTech FEC, Berlin Germany