The reference configuration deployment architecture supports Access Manager session failover, as described in Session State Availability. It does so by configuring Access Manager to use Message Queue and a highly available database to store and replicate Access Manager session state.
If your business solution permits users to log in again to reestablish a session after a service failover, then Access Manager session failover is not a requirement for your portal service deployment. If that is the case, you do not need to configure Access Manager for Access Manager session failover, and Message Queue would not be included as a component in the Access Manager service module. This approach would change the implementation of the Access Manager service module by not requiring the procedures in Implementing Session Failover for Access Manager .