what about 48 bits?

Stephen Sprunk stephen at sprunk.org
Tue Apr 6 21:39:44 CDT 2010

On 05 Apr 2010 12:43, Valdis.Kletnieks at vt.edu wrote:
> On Mon, 05 Apr 2010 13:29:20 EDT, Jay Nakamura said:
>>>> I would have attributed the success of Ethernet to price!
>>> You've got the causality wrong -- it wasn't cheap, way back when.
>> I remember back in '93~94ish (I think) you could get a off brand 10BT
>> card for less than $100, as oppose to Token Ring which was $300~400.
>> I can't remember anything else that was cheaper back then.  If you go
>> back before that, I don't know.
> Steve is talking mid-80s pricing, not mid-90s.  By '93 or so, the fact
> that Ethernet was becoming ubiquitous had already forced the price down.

Ah, but what _caused_ Ethernet to become ubiquitous, given the price was
initially comparable?  The only explanation I can think of is the raft
of cheap NE2000 knock-offs that hit the market in the late 1980s, which
gave Ethernet a major price advantage over Token Ring (the chips for
which all vendors _had_ to buy from IBM at ridiculous cost).  That, in
turn, led to mass adoption and further economies of scale, pushing the
price lower and lower in a virtuous cycle.  Still, lots of shops stuck
with TR well into the mid- and even late 1990s because Ethernet didn't
perform as well as TR under moderate to high utilization by multiple
hosts, not to mention IBM's insistence that TR was required for SNA.  It
wasn't until Ethernet switching came out, mostly solving CSMA/CD's
performance problems and eventually leading to full-duplex operation,
that it was entirely obvious which was going to win, and I spent several
years doing almost nothing but helping large enterprises convert to
Ethernet (usually with the help of DLSw).  By that point, off-brand
Ethernet chips cost _less than 1%_ of what IBM's TR chips did, thanks to
competition and sheer volume, so vendors had started including them "for
free" on every PC and server, and that was the final nail in TR's coffin.

(LocalTalk, ARCnet, and a variety of other physical layers suffered a
similar fate, but unlike IBM, their backers quickly switched to Ethernet
when they realized they couldn't compete with it on price _or_ on
performance given their limited volumes, so those deaths were more
sudden and absolute than TR's.)

As to why no other technology has managed to dislodge Ethernet, though,
I think it's fairly clear that's because the various successors to
10BaseT have all maintained the same connector and the same framing,
which makes for trivial upgrades that deliver regular (and significant)
performance improvements as customers' equipment replacement cycle turns.


Stephen Sprunk         "God does not play dice."  --Albert Einstein
CCIE #3723         "God is an inveterate gambler, and He throws the
K5SSS        dice at every possible opportunity." --Stephen Hawking

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