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From: Mills@UDEL.EDU.UUCP
Newsgroups: mod.protocols.tcp-ip
Subject: Re:  IP over x.25
Message-ID: <8704032140.a012362@Huey.UDEL.EDU>
Date: Fri, 3-Apr-87 21:40:49 EST
Article-I.D.: Huey.8704032140.a012362
Posted: Fri Apr  3 21:40:49 1987
Date-Received: Sun, 5-Apr-87 08:25:25 EST
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Approved: tcp-ip@sri-nic.arpa

Gerd,

I assume the X.25 connection is broken somewhere in the public-net path, perhaps
in either of the national X.25 nets or in the X.75 gateway(s). To break that
after two minutes of inactivity sounds broken in the extremus, especially if
the restoration costs real Geld. On the other hand, your opens are cheap, about
equivalent to twenty seconds of connect time, so maybe things aren't that bad,
at least if the reset/open can be made transparent to your TCP/TELNET connection.

Come to think of it, if the MILNET/ARPANET congestions is as fierce as you
report, it might be cheaper to encapsulate IP datagrams as fast-select packets,
rather than go through the complete virtual-circuit clankery. This might be
a fun puddle to go wading in. Lemme see, at twenty (roundtrip!) packets per 
Mark, you would break even at about seven minutes. Maybe not too bad under
current conditions...

While it is in principle possible to do all kinds of things which might convey
the connection-closed state at the VAN gateway to the end systems, I suggest
this would not be very useful if only to stimulate a re-open. If it really does
come down to keeping the connection open, the VAN driver could be modified to
send ICMP echoes to its peer just often enough to reset the VAN timers. Be
advised you did not hear me say this, for I am not present and will instantly
disavow any attribution of such nonsense to mine lips. Now, I hope that will
keep the truthspeakers from my throat. Yes, and stop the ICMP echoes after
a period when no other traffic is present. [Gaggg]

Dave