Re: World's First Fuel Cell-Powered Train Locomotive Slated for 2008

From: Scott A Crosby (scrosby_at_cs.rice.edu)
Date: 08/19/04 

Date: 18 Aug 2004 23:40:35 -0500

On Wed, 18 Aug 2004 21:59:58 -0400, "Ian St. John" <istjohn@noemail.ca> writes:

> > And Ethernet is not the sole end of TCP/IP. One is a media layer,
> > the other is up from that (TCP is actually a separate layer 'on top'
> > of the IP layer). TCP/IP can be (and often is) run over other media
> > layers besides Ethernet (e.g. TokenRing, Apple-Talk, even simple
> > UUCP).
>
> Point is that internet is layered on Ethernet. No foundation, no layer.

End-host connectivity to the internet has usually been Ethernet,
though with Wavelan, that may change. This was done because ethernet
was cheap and 'good enough' for local area networking. But once data
leaves the LAN, its going over ADSL, SDSL, T1, T3, WDM, DWDM, OC-3,
OC-48, OC-192, PPP links or any of another dozen L2 link-layer
protocols. Although Gigabit Ethernet has 'Ethernet' in its name, I
don't believe it uses a shared medium for communication, making
calling it with the term 'Ethernet' a misnomer. As it is, with modern
switched full-duplexed networks, 100baseT Ethernet is effectively a
point-to-point protocol with no collision or physical-layer link
contention.

FYI, the Kahn and Cerf paper outlining TCP is two years older than the
first drawing by Metcalf describing ethernet.

Scott

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