Path: utzoo!utgpu!watserv1!watmath!att!pacbell.com!ames!rex!samsung!cs.utexas.edu!calvert
From: calvert@cs.utexas.edu (Kenneth L. Calvert)
Newsgroups: comp.protocols.tcp-ip
Subject: connect "collisions" in TCP
Keywords: simultaneous, TCP features
Message-ID: <1064@muleshoe.cs.utexas.edu>
Date: 30 Jan 91 15:58:31 GMT
Organization: U. Texas CS Dept., Austin, Texas
Lines: 20


In TCP, the result of a "connect collision" (i.e., two peers
"simultaneously" attempting to open a connection to the same pair
of ports) is a single connection.  I have two questions:

0.  My impression is that the Berkeley Unix sockets interface (to TCP)
precludes deliberate use of this "feature".  Have I missed something?
(The implementation does the right thing when SYN is received in state
SYN_SENT).

1. Can anyone cite an application or higher-level protocol that
makes use of (or could, if it were possible) this fact,
i.e. permits users to establish connections symmetrically?
I can think of one possibility: the FTP data connection,
but I don't think it works that way.

Don't need to do this myself -- just curious.

Ken Calvert
calvert@cs.utexas.edu