[ih] Ethernet, was Why TCP?

[Noel Chiappa]

    > From: "John Levine"

    > As we all know, Ethernets worked just fine. A lot of people didn't
    > believe it until they saw it

In defense of the Ethernet sceptics, most Ethernets were operated at traffic
levels where the collisions which theory predicted at high traffic levels
weren't a problem.

Liba Svobodova (at MIT at that point) did a bunch of analyses (this would be
ca. '78 or so) which showed that at low traffic levels, it would be fine, and
that only at high traffic levels would there be issues. Her analyses, AFAIK,
were right on target.


And of course the _real_ advantage of rings was not so much in the
token-passing access method, as in the analog lower level they used - all
simple point-point links. (Great for optical, BTW.)

Which is why today's 'Ethernet' networks are not (when you lift the covers)
really CSMA-CD networks: they actually consist of lots of little packet
switches connected by point-point links. I.e. the current systems use the best
of both approaches (the simple access mechanism of Ethernet, and the simple
point-point links of rings).

The only parts of 'Ethernet' left are the packet format, and the host/network
interface standard. As always, the interface is left when the equipment on
either side has changed out of all recognition - check out the screw base on a
mains AC LED bulb...

	Noel