Hans-Peter,

>While backing up the full information store (about 9GB) we always >receive
the message :
>'ANS1017E (RC-50) Session rejected: TCP/IP connection failure'.

All evidence seems to indicate that there is a problem getting the data to
the ADSM server.
The server times out in a receive-wait state and the client complains of a
TCP/IP error sending
data.  I think you need to turn on a tcp/ip trace to see where in the
network the problem is
happenning.   Even though your network people say there is no problem in
the network,
they should trace the tcp/ip session to see where the packets sent by the
client are getting
hung up.

Chris Zaremba
ADSM Agent Development
internet  zaremba AT us.ibm DOT com