Path: utzoo!attcan!uunet!lll-winken!lll-lcc!ames!haven!uvaarpa!babbage!mac3n
From: mac3n@babbage.acc.virginia.edu (Alex Colvin)
Newsgroups: comp.dcom.lans
Subject: Re: Token Ring (was: Re: Info on LANs)
Summary: aethernet, llc
Message-ID: <484@babbage.acc.virginia.edu>
Date: 4 Jan 89 23:24:53 GMT
References: <12786@cup.portal.com> <920001@hposdl.HP.COM> <10777@s.ms.uky.edu> <13137@bellcore.bellcore.com>
Organization: University of Virginia
Lines: 50

> I suspect you are referring to Logical Link Control Type 2 (the
> connection-oriented version closely resembling LAPB). However, I don't
> personally know anyone using it. In fact, I don't know anyone using LLC Type
> 1 either; the original Blue Book (DEC-Intel-Xerox) Ethernet spec works just
> fine for us. In my opinion, the world would be a better and less confusing
> place if the IEEE 802.3 committee never existed.

Well hello!  I use LLC type 1 (unack'd DG).
But not 2 or 3 - my token ring isn't noisy enough either.

It's true that the ACK should be done at a higher end than the link.
This can win by ACK'ing a numberof packets in one.  BUT, many implementations
can't get that to happen, so you wind up with an ACK packet anyway, only it's
bigger and later.

Anyway, the LLC stuff is 802.2, it's generic to IEEE, not to CSMA/CD.

> Anyone with experience in writing drivers can tell you that performance
> depends much more strongly on the hardware design of the controller than
> anything else.

Actually, the design of the driver, particularly the client interface, is
probably even more important.

> He was able to run the useful throughput of the LANCE chip very close to 10
> megabits/sec, but the Intel chip did no better than about 5 megabits/sec. It

I'm impressed! What kind of memory interface?  I can't get more than about
3Mb/s across a PC bus or Multibus.

> >>"Ethernet works in practice, but not in theory".
> I was taught that when many people can confirm that something happens in
> practice that doesn't match the predictions of a theory, then it is usually
> safe to assume that there's something wrong with the theory.

In this case, a theory says that ethernet can't run more than 1/e*10Mb/s
is based on an unrealistic (but tractable) model - an infinite number of
unsynchronized processes.  In real life, stations that communicate are
probably loosely synchronized.

> the moment, Ethernet is clearly superior to the token ring in doing what it
> is designed to do -- providing simple, reliable and relatively inexpensive

Mostly it's a mature technology.

> computer networking over a small local area. Token rings, because of their
> more complex design, are inherently more expensive and less reliable, but

That's that IBM approach.  Not all token rings are as hairy.  I like Proteon's
proprietary rings, at 10 and 80 Mb/s.