Geoff -

It would be helpful if you would reply with the results of specific
suggestions. Last week I suggested a co-resident client-server test
using local address 127.0.0.1, which would thus eliminate external
networking/routing and exercise only the TCP/IP stack. If that
doesn't work and the port still shows its Listen state, it tends to
suggest a problem in the TCP/IP stack. However, we've not heard of
anyone else having such a problem, so that seems doubtful.

I've seen an AIX system experience networking hangs (at the AIX 4.x
level) before: I recall that I did an ifconfig down and then up on
the interface, which cleared that instance.

Since the problem came with site changes in router/switch
configuration (you cited firewall changes), that could well be the
issue. It may be that the device may be misconfigured in QoS terms
where after a certain amount of traffic the device denies further
transmissions.

Another obvious thing you can do to try to isolate the problem is
change the TCPPort number of the TSM server and a test client from
1500 to something else, to see if it's a port number issue.

  Richard Sims