Hi Kalyan,
I suppose that you are talking about HTTP Sessions. HTTP Session are managed and configured at AppServer level (you have different levels, webcontainer, application or module).
You can persist session on database or in memory-to-memory replication
Configuring HTTP Sessions
https://www.ibm.com/support/knowledgecenter/SSAW57_8.5.5/com.ibm.websphere.nd.doc/ae/container_httpses_goal_administering_tasks.html
WebServer Plugin mantain session affinity to servers in a cluster.
Hope this helps. Tell us if you need more support
Regards