Hi Sunil,
beside of using the "Priority Group Activation" feature (already mentioned by Mohamed) to establish a primary/secondary configuration with automatic failover/failback, you could also use a "DST_IP" persistence profile with long timeouts to support a active/passive configurations with automatic failover but without failbacks.
Depending on your detailed requirements of autmatic failovers/failbacks and the control and visibility of the current active node, it may be also required to write certain iRules to control the active node by using a
[table]
entry (e.g. initiating a failover only after 30 seconds inactivity, manually switching the current maste node, etc.).
Do you have any special failover/failback requirements? Or are you fine with the Primary/Secondary failover/failback apporach of the "Priority Group Activation" feature?
Cheers, Kai