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From: Lepreau@UTAH-20.ARPA (Jay Lepreau)
Newsgroups: mod.protocols.tcp-ip
Subject: Re: SYN with a window size of zero
Message-ID: <12176159649.11.LEPREAU@UTAH-20.ARPA>
Date: Sat, 18-Jan-86 03:42:36 EST
Article-I.D.: UTAH-20.12176159649.11.LEPREAU
Posted: Sat Jan 18 03:42:36 1986
Date-Received: Sun, 19-Jan-86 05:42:22 EST
References: <[USC-ISI.ARPA]16-Jan-86.21:44:33.CERF>
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Organization: The ARPA Internet
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Approved: tcp-ip@sri-nic.arpa

This recently came up in another context: the TAC's put garbage in the
window field in their initial SYN, all the way up to 64K.  This raised
havoc with some of our hosts which remembered the max window size they'd
ever seen.  I talked to the TAC folks at BBN who maintained that since
the window is only defined relative to the ack seq number, the window is
meaningless unless ACK is set, and therefore it's not their bug, it's
ours.  Sounds plausible, so we fixed it here.  (A zero initial window
is quite good behavior, in contrast with the TAC's, which are clearly
violating the robustness principle.)
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