[e2e] What if there were no well known numbers?

Christian Huitema huitema at windows.microsoft.com
Fri Aug 4 14:23:44 PDT 2006

> In any event, I got the impression that TCP pretty much just followed
> NCP's lead on this. Is there anyone here who was around for the NCP
> design who can comment on what NCP's reasons were for well-known
> My guess would be lack of infrastructure (as DPR points out, that was
> before there was even HOSTS.TXT).

That was certainly not the only reason. At about the same time, the ISO
protocols were designed to use a "Transport Service Access Point
Identifier", with pretty much the semantic that Joe is proposing in
"draft-touch-tcp-portnames-00.txt". These protocols would negotiate a
pair of random identifiers for each connection. Some thought that having
port numbers that serve as both "end point identifier" and "connection
identifier" was a better design. Traffic analysis is definitely easier,
and there are advantages in some scenarios, e.g. simultaneous connect.

-- Christian Huitema 

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