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From: Mills@CISL-SERVICE-MULTICS.ARPA
Newsgroups: mod.protocols.tcp-ip
Subject: Zero window probes
Message-ID: <851108205728.000456@CISL-SERVICE-MULTICS.ARPA>
Date: Fri, 8-Nov-85 15:57:00 EST
Article-I.D.: CISL-SER.851108205728.000456
Posted: Fri Nov  8 15:57:00 1985
Date-Received: Tue, 12-Nov-85 04:31:41 EST
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Approved: tcp-ip@ucbvax.berkeley.edu


          I am wondering what the appropriate action for a TCP
connection that is sending out zero window probes and
recieveing ACKS for the last octet of the window.  For a small
amount of time you obviously want to keep the connection
around in case the window opens. The real question comes in
when the window has been closed for some time.  One argument
is, that if you are recieving valid ACKS the other end is
alive so keep the connection open.  The other is that if has
been that long since you were able to transmit something is
probably wrong with the connection.  In looking in RFC-793
this issue seems to be rather glossed over.  I am using the
September '81 version of the RFC form the protocol transition
workbook.  Is this the up-to-date spec?   Any information or
pointers into the specs would be very helpful.

Thanks,  John Mills