Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!tut.cis.ohio-state.edu!ucbvax!A.ISI.EDU!CERF
From: CERF@A.ISI.EDU
Newsgroups: comp.protocols.tcp-ip
Subject: Re: Ignorant question - multiple connections within TCP ports?
Message-ID: <[A.ISI.EDU]21-Jul-89.19:24:47.CERF>
Date: 21 Jul 89 23:24:00 GMT
References: <4908@ucdavis.ucdavis.edu>
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The CALLING PORT is supposed to be selected at Host A to be distinct
for each TCP connection initiated. Thus, the well-known target
Host B port (513) can be the same for both connections, but the
two are distinguished by the port pairs:

Connection 1: Port A1 on Host A, Port 513 on HOst B
Connection 2: Port A2 on Host A, port 513 on Host B.

The second option you cite is flat wrong.

Vint Cerf