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: token rings in general, and 802.5
Message-ID: <483@babbage.acc.virginia.edu>
Date: 4 Jan 89 23:05:58 GMT
References: <12786@cup.portal.com> <920001@hposdl.HP.COM> <10777@s.ms.uky.edu> <18659@agate.BERKELEY.EDU>
Organization: University of Virginia
Lines: 37

In article <18659@agate.BERKELEY.EDU>, glass@tehran.berkeley.edu (Brett Glass) writes:
> In <10777@s.ms.uky.edu>, David Herron writes:

> All IEEE 802.5 Token Rings have the same topology.

There are other token rings.  I use a Proteon proNET-10, which has similar
wiring, except for the dual-contrarotating topology.

> A 4-Mbps Token Ring will outperform a 10-Mbps Ethernet under
> heavy loads because of the absence of collisions. And the

Now you're getting into the benchmarking fog.  It depends STRONGLY on the
kind of load.  There's a lot of overhead traffic in 802.5

> priority scheme guarantees that important messages arrive
> quickly. Read the section titled "Bravery Under Fire" in the
> article.

sort of...  If the ring is lightly loaded, then priority isn't significant.
If the ring is heavily loaded, then the priority information arriving in
the token is likely to be out of date.

> 
> > OOooh  AAaah, they've raised the speed up to 16Mbps ... that's
> > still the same ball-park as ether.
> 
> That's a 60% improvement, not counting the additional gains from
> the lack of collisions. Perhaps this is why Sun Microsystems was
> one of the original test sites for the 16-Mbps ring.

A 16Mb/s ring will almost always carry more traffic than a 10Mb/s Aether.

The performance visible to any station, however, depends mostly on the
hardware and software.  The network designers worry about access delays in
the range of microseconds.  Then the adaptor design loses a few msec in
data transfer with the host.  Last comes the software and operating system,
which blows off a few 100msec.