Ethernet math (Was Re: MWC's Coherent - A Lemon...)

[John C. Archambeau]

hwajin at wrs.wrs.com (Hwa Jin Bae) writes:
>Which point are you trying to make?
>
>Let me help:
>
>Your point #1: a "real" ethernet with more than 10 machines will have at most
>3Mbit/sec performance rate on a good day.   --- My data indicates this is
>wrong.  Give me some of your data that proves otherwise.  No rhetorics, please.

My data is my findings via experience in hooking machines to an ethernet.  I
have yet to see an ethernet perform a consistant (key word here) throughput of
more than 3 Mbit per second.  Last October I added a Sun 386i/250 to an
existing ethernet of less than 10 machines.  The best throughput I've seen on
that wire was 4 Mbit per second.  You tell me why it was dropping packets like
crazy.  The customer we sold the Sun 386i has talked to Sun about it and they
can't even tell him why his ethernet has a sloppy throughput.  Again, there's
no such thing as an expert.  And the ethernet is primarily Suns with a pair of
VAX'es.  If you have this magic formula for getting 6+ Mbits per second on an
ethernet, I'd sure as hell love to hear it.

When *I* start seeing consistant throughputs of more than 3 or 4 Mbits per
second on an ethernet then I'll agree with you, but until then I write all of
this off as the overhead of ethernet.  I don't care what your throughput is or
what AST gets on his pair of Sun 3/60's, but what I see when I go and add or
setup a network.
 
     // JCA

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