Thanks Malay.

It's not connecting to any other server except DB.

I have traced the session for more than 2 hours and find nothing in the trace file.

Some thing is happening in the DB which I am not able to figure out. Because, log switch is happening once in every 2 minutes and undo records used and undo blocks used are keep growing.

when i query dba_rollback_segs, Undo segments 12$ and 13$ are offline since long time but 11$ is missing and 10$ is growing steadily.

SQL> select owner,tablespace_name,segment_name,status from
dba_rollback_segs;

OWNER TABLESPACE_NAME SEGMENT_NAME
STATUS
------ ------------------------------ ------------------------------
----------------
SYS SYSTEM SYSTEM
ONLINE
PUBLIC UNDOTBS1 _SYSSMU1$
ONLINE
PUBLIC UNDOTBS1 _SYSSMU2$
ONLINE
PUBLIC UNDOTBS1 _SYSSMU3$
ONLINE
PUBLIC UNDOTBS1 _SYSSMU4$
ONLINE
PUBLIC UNDOTBS1 _SYSSMU5$
ONLINE
PUBLIC UNDOTBS1 _SYSSMU6$
ONLINE
PUBLIC UNDOTBS1 _SYSSMU7$
ONLINE
PUBLIC UNDOTBS1 _SYSSMU8$
ONLINE
PUBLIC UNDOTBS1 _SYSSMU9$
ONLINE
PUBLIC UNDOTBS1 _SYSSMU10$
ONLINE
PUBLIC UNDOTBS1 _SYSSMU12$
OFFLINE
PUBLIC UNDOTBS1 _SYSSMU13$
OFFLINE

13 rows selected.
I am suspecting some thing wrong with my undo table space. does it make sense if i switch the system to new undo table space?

Thanks,