Xref: utzoo comp.os.vms:9207 comp.sys.hp:1130
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From: marius@rhi.hi.is (Marius Olafsson)
Newsgroups: comp.os.vms,comp.sys.hp
Subject: Re: CMU IP/TCP V6.3 problem: uVAX <-> HP <-> HLH Orion
Message-ID: <453@krafla.rhi.hi.is>
Date: 6 Oct 88 22:13:02 GMT
References: <2969@mva.cs.liv.ac.uk>
Organization: University of Iceland
Lines: 34

From article <2969@mva.cs.liv.ac.uk>, by keith@mva.cs.liv.ac.uk:
> We have quite a major problem in getting HP 9000/300 equipment to talk
> TCP/IP with a microVAX II running VMS V4.7 and CMU IP/TCP V6.3 over
> ethernet.
> 
> Basically, FTP and TELNET connections don't seem to last very long - the
> microVAX aborts with TCP Receive errors. ..

The CMU-TEK implementation periodically sends so-called "inactivity 
probes" over its connections to ascertain that the connection is still
alive. It is our experience that HP-UX always aborts the connection 
upon receiving these probes. To quote from the CMU-TEK code:

	                           ............ Currently, we will send
	an unacceptable segment with SYN and ACK on with a bogus sequence
	number. According to the TCP spec, such a segment should either
	generate an ACK with the correct sequence numbers or should generate
	an RST if the connection does not exist.

The problem is that HP-UX always generates RST. It would be nice if someone
from HP could comment wether this is a case of different interpretation of
the TCP spec or a bug in HP-UX.

Anyway, there does not seem to be a way to turn this off in CMU-TEK, and
the only way we had to make the HP-UX/CMU-TEK combination behave was to
patch CMU-TEK to eliminate these "inactivity probes". Mail for details
if anyone is insterested.

Our config (11/780 VMS 4.7+CMU-TEK-6.3 HP-9000/840 HP-UX 1.2)

--
Marius Olafsson 		Internet: marius@rhi.hi.is
University of Iceland		Non-MX:   marius%rhi.hi.is@uunet.uu.net
				UUCP:     {mcvax,enea,uunet}!hafro!rhi!marius