Mobility Domain Topologies
You can configure a mobility domain in the following scenarios:
- Mobility domain without
                availability
 
- Mobility domain with availability
 
- Mobility domain with session
                    availability

Note   
When
                                                  configuring a mobility domain with availability or
                                                  session availability, synchronize time on all the
                                                  wireless controllers that are part of your
                                                  mobility domain. For more information, see Configuring Network Time. 
Mobility Domain with Fast Failover and Session Availability
                        Features
                    
                    
                    
                 
 
- The user‘s home session is with Controller1.
 
- When the user roams from
                wireless AP 1 to wireless AP 2, he establishes his home session with
                Controller2.
 
- When the user roams, AP 1
                receives a notification that the user has roamed away following which it marks the
                user session as “inactive”. Consequently, no statistics are sent to the Controller 1
                for that user.
 
- In response to the heart
                beat message from the mobility manager (Controller 3), the Controller 2 sends
                updates that the user has a new home on Controller 2. Upon receiving the updates,
                the mobility manager updates its own tables.

Note   
The mobility
                    manager‘s heart beat time is configurable. If you are configuring a mobility
                    domain with session availability, you should configure the heart beat time as
                    one second to enable the mobility manager to update its tables
                quickly.
 
 
- If a failover takes place,
                and the user is still associated with AP 1:
                    - AP1
                        fails over, and establishes an active session with Controller 2.
 
                    - In
                        response to the heart beat message from the mobility manager (Controller 3),
                        the Controller 2 sends updates to the mobility manager on the failover AP
                        and its user.
 
                
 
- If a failover takes place,
                and the user has roamed to wireless AP 2:
                    - As part
                        of roaming, the user‘s home session moves from Controller 1 to Controlle
                        r2.
 
                    - AP1
                        establishes active session with Controller 2. AP  2 is not impacted by the
                        failover.