Path: utzoo!utgpu!watmath!clyde!att!osu-cis!killer!ames!haven!decuac!hadron!jsdy
From: jsdy@hadron.UUCP (Joseph S. D. Yao)
Newsgroups: comp.protocols.tcp-ip
Subject: Uniq <=> Ultrix
Summary: need help with odd problem
Message-ID: <828@hadron.UUCP>
Date: 10 Jan 89 13:14:51 GMT
Reply-To: jsdy%hadron.UUCP@uunet.UU.NET (Joseph S. D. Yao)
Organization: Hadron, Inc., Fairfax, VA
Lines: 34

I'm hoping that this will sound familiar to someone, who will then
send me mail (since I don't get this far in my .newsrc often).

A problem was reported to and observed by me, in sending certain mail
messages from VAXen running Ultrix 2.2 to a VAX running System V
Release 2 Version 2 (modified by me) with Uniq's Passage software
(again modified by me in places, to make it work at all).  After a
number of observations, it became obvious that only "large" (not yet
quantified) messages were failing, and the SMTP program on the Uniq
side was getting an error message, "URESET - network connection
aborted and reset".  Similarly large messages worked fine among Ultrix
2.2 machines.

The Ultrix 2.2 machines are running a - possibly early - version of
BSD 4.3 network code, while the Uniq code appears to be slightly
modified BSD 4.1.

Instrumentation of the Uniq side shows that the TCP level is receiving
several packets perfectly reasonably, then all of a sudden getting a
packet whose sequence number is 1024 more than expected!  At this
point, of course, it stops and waits for the next one ... which never
arrives.  This 1024 over is not a bit set - it is whatever-odd-number
plus 1024 (i.e., there is bit carry and so forth).  Since attempts to
re-receive the "proper" packet fail, it then times out and resets the
connection.

Any takers?  Mucho obligato if so.  Thanks to all...

	Joe Yao		jsdy@hadron.COM (not yet domainised ???)
	hadron!jsdy@{uunet.UU.NET,dtix.ARPA,decuac.DEC.COM}
	arinc,att,avatar,blkcat,cos,decuac,dtix,\
	ecogong,empire,gong,grebyn,inco,insight, \!hadron!jsdy
	kcwc,lepton,netex,netxcom,phw5,rlgvax,	 /
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