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From: mishkin@apollo.uucp (Nathaniel Mishkin)
Newsgroups: comp.protocols.tcp-ip
Subject: Re: Ethernet Suffering
Message-ID: <34bd5209.c366@apollo.uucp>
Date: Fri, 8-May-87 10:49:00 EDT
Article-I.D.: apollo.34bd5209.c366
Posted: Fri May  8 10:49:00 1987
Date-Received: Sat, 9-May-87 18:42:30 EDT
References: <8705070548.AA10268@ucbvax.Berkeley.EDU>
Reply-To: mishkin@apollo.UUCP (Nathaniel Mishkin)
Distribution: world
Organization: Apollo Computer, Chelmsford, MA
Lines: 29

I found all this discussion about loaded ethernets pretty interesting.
Having used Apollos (both in and out of Apollo Computer Inc.) for the
last ~5 years, I've become pretty familiar with the vices and virtues
(much of the former) of token ring networks and often wondered why we
wouldn't just be better off with ethernet.  I think the recent discussion
in this group highlights some of the virtues of token ring networks.
I was fairly astonished to hear read one basically can run no more than
(based on the various estimates) 8-15 diskless workstations (of some
manufacture) on a single ether.  I shudder to think of the cost (in money
and performance) of *requiring* routers/bridges and internetwork topology
for a relative small "work group".  You just don't have these problems
in a token ring.  Token rings guarantee fair access to the medium and
as a result can run successfully with consistently higher average loads.

And forget diskless workstations for a minute.  How about doing file system
backups over the net?  There's a fine bit of load; and it's not bursty
like diskless workstations.  In our multi-hundreds of gigabyte environment,
backups (like love) are forever.

I also thought the comment about how improved caching would help matters
was interesting.  Of course, proper caching requires correct cache
validation to ensure that you're reading valid data.  Not all distributed
file systems implement such correctness guarantees.  For example, Apollo's
distributed file system does, but NFS doesn't.
-- 
                    -- Nat Mishkin
                       Apollo Computer Inc.
                       Chelmsford, MA
                       {wanginst,yale,mit-eddie}!apollo!mishkin