Via:         000010623000.F; 12 JAN 93 20:27:47 GMT
X-Mailer:    ELM [version 2.3 PL11]
Newsgroups: bit.listserv.novell
Date:         Tue, 12 Jan 1993 20:27:34 GMT
Reply-To:     Novell LAN Interest Group <NOVELL@SUVM.BITNET>
From:         Richard Letts <R.J.Letts@SALFORD.AC.UK>
Subject:      Re: Token Ring vs. Ethernet

Alex Breen writes....
>
>
> "Bob.Cowling" <23130MGR@MSU.BITNET> writes:
>
> >Token ring is better for a smaller network.  By small and the reasons behind
> >my comment is that on a large network an individual system has to wait for
 the
> >token to come 'round.  And the maintenance could be more because of the ring
> >architecture.  When you have two runs to keep track of instead of just one
> >that adds to the trouble and complexity.  But in defense of TR, I was told
> >that for a small (What do you call small) TR can beat the pants of ethernet.
>
>      I disagree.  I would say just the opposite!!  My experience has been
> that ethernet is good for smaller networks, while token ring is better for
> larger networks.  Ethernet slows down a lot more under heavy loads
> because of the many collisions.  Token ring seems to run at about the
> same speed regardless of the traffic.  No, I would definately say that
> ethernet is the choice for a smaller network while token ring has other
> advantages which suites it for a larger network.
>      As far as relative ease to setup, ethernet is easier to setup and
> manage.  Token ring is far more robust and stable in my experience.  Note
> I am not saying that one is "better" than the other.  I have been throught
> that war many times before.
>

The difference betwenn ethernet and Token ring networks is the size it is
allowed to grow BEFORE you add routers or bridges to it.

Having run a 500 node repeatered network, and running a 2000 routed network
I can assure you that trouble-shooting the former was a PAIN.

The way 4MB token ring works is :
        1. The stations agree how long they can hold the token
        2. once you have the token you transmit as much data as you want
        during that time; you also discard all received data, as its your
        own.
        3. you wait for all the data you sent to get back to you
           [receivers set a bit saying the've seen the data]
        4. when you have received all the data you sent you release the token

On a LARGE network the time between when you should stop
sending, and when you release the token is significant, and during this time
the network is idle. [ actually your data is 'draining' out of it]

The way 16MB token ring and FDDI works is different:
        1. The stations agree how long they can hold the token
        2. once you have the token you transmit as much data as you want
        during that time
        3. you release the token
        4. you discard any data you receive whilst holding the Token
        [any data you receive whilst you have the token MUST have been
        received by the recipient, as the token FOLLOWS the data around the
        network]
This is known as early-release and keeps the ring more fully occupied.

Ethernet works like this:
        1. If its free use it
        2. if we've tried n times to send the data discard it
        3. if its not free wait a random time, and go to 1
        [sounds like chaos compared to TR !!]

generally: for small, loaded networks 4MB token ring is ok
           for large, loaded networks ethernet will beat 4MB Token-Ring
           for large, loaded networks 16MB Token-Ring will beat ethernet

BUT the point is NO-ONE should build a LARGE network without the use
of routers and/or bridges. These partition the traffic and, if the network is
designed right, heavy load in one part doesn't affect the rest.

--
Richard Letts
Network Manager
University of Salford               Email: R.J.Letts@salford.ac.uk
United Kingdom                      Phone : +44 61 745 5252
United States of Europe
Comments: Gated by NETNEWS@AUVM.AMERICAN.EDU