We have some very strange session lost errors showing up on our client.
First the particulars:

Server is AIX 4.3.3 ML 10, TSM V4.2.2
Client is AIX 4.3.3 ML 10, TSM V5.1.5.5 (upgraded several times from V4.2.2
at TSM Support request to deal with this problem)

Client and server are on separate 100 Mb full duplex subnets.

There are other AIX 4.3.3 ML 10 clients on the same subnet as the failing
client that do not get any errors. network option (no) settings are the same
on both clients. dsm options have been modified on the failing client to
reflect those on the successful client in troubleshooting to ensure
differing options are not causing a problem.

The client having the problem will start a backup (incremental or archive,
scheduled or manual) and suddenly "freeze" for several minutes before
severing the socket connection and will proceed to reconnect/timeout almost
continuously. Sometimes it appears to stop in the same spot, other times
not. There doesnt appear to be any reason why certain files would cause a
problem (i.e., they are not open at the time).

Any idea what i can check? I have tried everything... all sorts of settings
in dsm.sys and no settings. There are not any errors reported on the system
itself. just "session lost" on the client and "session terminated" on the
server. Ive been working with IBM TSM Support for quite sometime and they
just keep wanting more traces and "upgrade to the latest client."

Im at my wits end.