Hi I had a 11g Database Server which is AIX and is 3-node cluster. I am trying to make sqlplus connection from my PC and opened two windows like one to RAC Service and another to Dedicated Connection to only one Node. I had idle_time to unlimited to the user used for connection to te database My both Sqlplus session was good for 30 minutes but after around 1hr +, I tried to check the sql, I got ORA-03135 on both. Can anyone point as what can be the issue. Also sqlnet.expire_time is set to 10 on the Server. This is affecting the application user also who are loading Data warehouse with batches and long one are failing. Any help is greatly appreciated. I provided some work done so far. Check there is no firewall between PC and Db server TIA Sanjay