[e2e] TCP Framing

[J. Noel Chiappa]

    > From: RJ Atkinson <rja at inet.org>

    > if the TCP checksum were bound to some form of host identifier other
    > than the IP address, TCP could provide that particular property quite
    > nicely. Obviously I'm influenced by conversations with jnc on this
    > particular point. It would be an interesting exercise to work out the
    > details for such an approach.

As part of the NSRG work, I have a basically-done I-D which worked out in
some detail how to do it. (I.e. down to specifying the mechanics of how you
do an upwardly compatible change to the TCP checksum, the format of a TCP
option to carry the host identifier in the SYN packet, etc, etc.)

It turns out you can do it with zero extra overhead in both (packet) space
and processing time - if you keep the same checksum algorithm - more if you
upgrade to a better one, as I recall Dave Reed wanted to do originally :-).
(In fact, a tiny bit less computing, if you're recomputing the partial
checksum of the pseudo-header at the moment.)

If people are interested, I can put it up on the web somewhere, or even
(gasp) turn it in as an I-D.

	Noel