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

Bob Braden braden at ISI.EDU
Fri Aug 4 15:54:40 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 ports? My guess would be
>lack of infrastructure (as DPR points out, that was before there was even

I was around during the NCP design, in the next building over from the CS
department where Crocker, Postel, Cerf, ... were laboring.  I attended
most of the NWG meetings and read the RFCs at the time.  So, here is
my opinion, but Steve Crocker himself is best qualified to answer this.

Remember that at the time there was no previous experience with designing
or implementing network protocols. (Well, I guess the Cyclades and maybe
the Cambridge folks were doing something, but it was not well known among
the UCLA grad students who designed NCP).  Crocker et al drew nice
schematic diagrams with process clouds communicating through ports.
How to name these ports?  Well, a 16 bit number (gosh, I forget,.. was it
an 8 bit number?) seemed like the most obvious thing to use, so that is
what they used.  A numeric port was a string of bits with no semantic
interpretation a priori, so it appealed to the reductionist approach that
was common in the early network designs.

Maybe this discussion should be posted to the history list.

Bob Braden

>         Noel

More information about the end2end-interest mailing list