X.25 to Milnet PSN problems - the continuing saga

Brian Kantor (brian@ucsd.edu)
5 Feb 88 13:24:54 GMT

A few weeks ago I mentioned here that we're having a problem with the
Milnet IMP we're connected to being completely unable to open X.25
virtual circuits to us, so only those VCs that we open to it will allow
data to pass to mailbridges and other hosts on the milnet.

We're still having the problem, and I wonder if anyone else has seen
this happening on their host? Misery loves company, maybe?

Our interface is an ACC6250 board (in a VAX780 4.3BSD), and the
people at ACC (especially Lars Poulson) have been extremely helpful
in attempting to get this problem resolved, but so far it isn't.

I'm told that a trace in the PSN code shows that the IMP wasn't even
trying to open the circuit to us, so it's probably in or related to the
PSN code and not the interface - especially since it just started
happening without us making and hardware or software changes. It DID
start around the time the Arpanet cut over to PSN-7, but we're on the

We're currently running a process that sends a single ping packet to
each of the Milnet mailbridges once every 45 seconds to ensure that the
X.25 VC stays open so that traffic will find an already-open VC instead of
blocking because it can't open one of its own.

Now that I've finished crying on your collective shoulders (waah), I'm
wondering if anyone else has seen any evidence of this happening to
them? I have trouble believing we've been singled out for this dubious

        Brian Kantor UCSD Office of Academic Computing
                        Academic Network Operations Group
                        UCSD B-028, La Jolla, CA 92093 USA
                        brian@ucsd.edu ucsd!brian ucsd!brian BRIAN@UCSD

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