From: rfranken@mcs213f.cs.umr.edu (Richard Brett Frankenberger)
Subject: Re: Token Ring vs. Ethernet
Date: Thu, 19 Nov 1992 19:36:51 GMT
Organization: University of Missouri - Rolla

In article <sige6ao@rhyolite.wpd.sgi.com> vjs@rhyolite.wpd.sgi.com (Vernon Schryver) writes:
>-Ethernet is still cheaper, and that is not likely ever to change.
 
True.

>-Ethernet is simpler and so more robust.  Any single ring scheme is a
> royal pain compared to ethernet.  The hassles of source routing and
> other token ring "features" must be experienced to be believed.

It's more robust?  Really?  What happens if a faulty transciever cable in
ethernet is messing up the entire line?  Nothing.  On Token-Ring?  The
workstation will remove itself from the ring.  I can bring down an ethernet a
lat easier than I can bring down a token-ring.  And I can get a token-ring back
up faster than an Ethernet.
 
Simpler?  No disagreement there, but that doesn't mean its better.  (It is
one of the reasons Ethernet is cheaper, but other than that, I don't see
any benefits from its simplicity).

The hassels of source-routing? No big deal ... I manage a WANof about 30      
TR's allsource-routed togethor (now being converted to routers).  Source
routing is no major problem (certainly less confusing that setting up
IP routing).  BUT, if you don't like it, you don't have to use it.
Anyway, source-routing is more like bridging than routnig (in several
ways), and in a large WAN, you are better off with routers anyway.
 
On ether net, you can get between segments one of two ways.  Transparent
bridges or Routers.  On token-ring, you have those two options PLUS  
Source-Routing.  Source-Routing is just another option.  You don't have
to use it.  (Yes, IBM's SNA over LANs is based on source-routing, but
that doesn't work over Ethernet normally anyway (yes, it can be done); but
you could use the same tricks to run it over Ethernet to run it over
token-ring without source-routing).
 
>-10MHz Ethernet is faster than 4Mb/s token ring.  A pair of 16Mb/s token
> ring stations can be 60% faster than a pair of ethernet stations,
> but mostly because of the underlying bandwidth.  At the (now) low
> speeds of ethernet and token ring, there is no interesting effeciency
> difference for stations (not hubs or switches) between packet sizes
> of 1500 and 16K.

Really?  On a 4 MBPs token-ring, I ran some large file copies at approx 1.5K and
4K packet sizes.  The 4K was about 25-50% faster (I can't remember exactly).
Of course, for smaller transactions, the difference is less, but still
noticable.  (This test was done with a lightly loaded Novell file server with
Packet Bursting (without packet bursting, the difference would be even more
pronounced).
 
Since someone is sure to bring this up, at heavy loads, ethernet's performance
is much worse than token-ring (too many collisions).  At very light loads,
Ethernet's performance is better (no waiting for tokens).  (I'm comparing
the topologies here independant of speed.  Of course 10MBPs is faster than 4MBpsand 16MBps is faster than 10MBps), butthe token-wait time is hardley ever
signifigant, and at the heacy loads required to break-down an ethernet, token-
ring will still work, but probably not with sufficent speed anyway.  (i.e. the
fact that token-ring doesn't break-down at high load is probably not a good
reason to pick it - if your wire is that heavily used, you need to sub-net
anyway)
 
>Ethernet is far more common and not significantly worse than token
>ring.  Since token ring is not significantly better (it can be argued
>to be worse since it is so much more fragile), token ring is dead in
>the long run.  The universe does not tolerate competing, largely
>equivalent standards forever; eventually the less common one disappears.
>
>Something that might hurry up the decades long death of token ring
>might be higher speed LAN's.  The short term winner(s) in those wars
>might have some effect on the numbers of new ethernet and token ring
>networks.  I thinking of cable plants and hubs that can be used for
>for both high and low speed links to the desktop.
 
Token-ring won't die.  Eventually, FDDI will be much more common than E-net and
TR.  FDDI is token-ring over fiber-optic, basically.  Then token-ring concept
is superior to the CSMA/CD concept used by Ethernet.  It is more robust,
have lots of error checking and correction built in, and  it is designed to
take heavy loads into account and share the bandwidth as fairly as
possible (Ethernet's method is just let them collide and we'll randomly pick
who gets to send).

>Vernon Schryver,  vjs@sgi.com

Bottom line,  You probably won't go wrong with either, but with token-ring, you
won't have to worry about one user sticking a pin through the cable and downing
the entire net.  (Not that that's a likely occurance, but it makes the point
about token-ring's robustness).  Ethernet will likely be cheaper, however.
 
         - Brett   (rfranken@cs.umr.edu)