[e2e] TCP Framing

[David P. Reed]

At 09:01 AM 3/26/01 -0800, Cannara wrote:
>Craig, this has been a common test for years, to see how old a "network-
>knowledgeable" student is.  Ask the what UDP means.  Prior to the interesting
>RFC Jeremy produced the "U" stood for just what it stands for in all other
>families of protocols that have datagram services -- "unreliable".  Somehow
>some Internet folks seemed to become sensitive, almost ashamed, of that very
>accurate and truthful engineering label, and turned to seek a "u"-word that
>had marketability.  I've yet to meet a user who knowingly "uses" a datagram
>protocol.  You're younger than I thought!

Alex - Craig may be young, but then I must be ancient at only 49.  Anyway, 
I was there at the meeting where we created UDP (and split TCP into the TCP 
and IP layers), in Marina del Rey in winter '77/'78.  We called it the 
"User Datagram Protocol" from the first, and the reason was to distinguish 
it from the IP layer, which was the "datagram protocol" not well tuned for 
users, since you couldn't demux sensibly on the "protocol" field to the 
correct "user process" aka "application program instance".  (I won't bore 
you with the radical idea that we had tried to force into TCP of using a 
64-bit process-specific address in IP, rather than a machine specific 
address - but memory cost a few pennies per bit then, so we were viewed as 
dangerously profligate).

Now there may have been some in the years after that that called it 
"Unreliable ...", but I'd suggest that only those who had fought against 
the idea that a base datagram function was useful would have stooped to 
that kind of propaganda.  Those of us who fought for a datagram protocol 
(the PARC people, Danny Cohen and the speech people, and the LAN people 
like me) used the term "best efforts", not "unreliable", to describe the 
delivery reliability of IP and UDP.

- David

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