Path: utzoo!attcan!utgpu!jarvis.csri.toronto.edu!mailrus!tut.cis.ohio-state.edu!ucbvax!BBN.COM!clynn
From: clynn@BBN.COM (Charles Lynn)
Newsgroups: comp.protocols.tcp-ip
Subject: Re:  Ignorant question - multiple connec
Message-ID: <8907281116.AA02028@ucbvax.Berkeley.EDU>
Date: 23 Jul 89 17:13:51 GMT
Sender: daemon@ucbvax.BERKELEY.EDU
Organization: The Internet
Lines: 14

One trick is to use the <n> high-order bits of the received acknowledgement
field as the hashing function, where <n> is selected based on the number
of simultaneous connections the implementation is intended to support.
Recall that the TCP gets to pick an initial sequence number "based on a
clock"; one "clock" might be an <n> bit counter that gets incremented
each time a new connection is created (skipping over values which are
still "in use").  One has to be a little careful, however, since all
received connection attempts will fall into bucket "0" (some might call
that a "feature"!) and would have to be moved to the appropriate bucket
when the SYN/ACK is sent, and if a connection sends enough data the
ACK will move to the "next bucket".  E.g., for <n> equal to 8 (a load
byte instruction), there would be 256 buckets, and a connection would
have to be moved to the next bucket (actually, it is in "two buckets"
for a little while) after 16 MBytes of data had been sent.