Description: When an entry in sessionSet table is created and no group has been added to this set yet or group has been created in this set but no session has been added yet the set state is 'idle'.

After a group has been created in this set and one session has been added to the group the set state becomes 'oos',i.e, out of service.

After successfully open socket and the session has sent START message to MGC, the state of the set will be changed based on whether this set is fault tolerant(FT) or none fault tolerant(NFT).

In NFT case the set state becomes 'activeIs'.

In FT case, if one session from a group received an active message from MGC and no standby message received from a session in the other group, the state of the set will change to 'activeIs'. On the other hand, if at least one session from a group received standby message from MGC and no other session from the other group received active message then the set state is transferred to 'standbyIs'. The set becomes 'fullIs' when at least one session from one group receives active message and at least one session from the other group receives standby message.

'unknown' is a state other than the above states.