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Path: utzoo!mnetor!yetti!eriks
From: eriks@yetti.UUCP (Eriks Rugelis)
Newsgroups: comp.dcom.lans
Subject: Re: connecting thin ethernet stations to a thick cable
Message-ID: <448@yetti.UUCP>
Date: Sun, 14-Dec-86 11:56:47 EST
Article-I.D.: yetti.448
Posted: Sun Dec 14 11:56:47 1986
Date-Received: Tue, 16-Dec-86 01:46:23 EST
References: <1097@uqcspe.OZ> <157@pta.OZ> <650@gvax.cs.cornell.edu> <136@piaget.UUCP>
Reply-To: eriks@yetti.UUCP (Eriks Rugelis)
Organization: York University Computer Science
Lines: 56
Keywords: node spacing, ethernet standards

i would like to thank those of you who have posted your about experiences
with 'butting' thick and thin ether-cables.  you have removed at least part
of my fears in this regard.  however,

In article <136@piaget.UUCP> jc@piaget.UUCP (John Cornelius, System Manager) writes:
>There should be little or no penalty for interrupting your thick cable and
>running a loop of thin cable to the workstations.  What may be most 
>appealing might be to leave the thick cable as a backbone and then have a 
>small number of fairly long local loops as in:
>
>=======|    |==============|    |============|    |===
>       |    |              |    |            |    |
>       X    X              X    X            X    X
>       |    |              |    |            |    |
>       X    X              X    X            X    X
>       |    |              |    |            |    |
>       --X---              --X---            --X---
    .
    .
    .
>-- 
>John Cornelius
>(...!sdcsvax!piaget!jc)

so what about the connection spacing considerations that are laid out in the
ethernet standard and that cause thick ether-cable to be 'marked in a
contrasting colour' at certain specified intervals?  my (probably limited)
understanding of the physics of the situation leads me to believe that this
is to avoid standing wave patterns in the cable (is this really off-base?)
if you intend to interrupt your thick ether-cable to insert segments of RG58,
do you scale the segments to   n * ((185/500) * thick cable node spacing) ?
do 'tails' from BNC T-connectors present in the 'loops' constructed in john's
example have to be considered in the thin-segment length equation?

i realize that a lot of people out there don't mind just plugging things
together to see what they can get away with.  i am one of those people,
whenever i can find the time.  however, debugging an ethernet after it has
been put in place and users have come to depend upon it is not my idea
of time well spent.  in this instance i would rather be aware of the limits
BEFORE i start pushing them.
---
           Voice: Eriks Rugelis
         Ma Bell: 416/736-5257 x.2688
      Electronic: seismo!mnetor!yetti!eriks.UUCP
               or eriks@yulibra.BITNET
Would like to be: Eriks.Rugelis@york.ac.can
           Quote: User-friendliness is one of the worst forms
                  of brutality known to man.
-- 
           Voice: Eriks Rugelis
         Ma Bell: 416/736-5257 x.2688
      Electronic: seismo!mnetor!yetti!eriks.UUCP
               or eriks@yulibra.BITNET
Would like to be: Eriks.Rugelis@york.ac.can
           Quote: User-friendliness is one of the worst forms
                  of brutality known to man.