This mib defines the SNMP objects to report the status of 
High Availability (HA) functionality in Cisco network 
management appliance devices. The HA functinality is
achieved via the redundancy of network management appliance
devices.

An network management appliance is a device which combines 
hardware and software to provide specific network management
services. Cisco WLSE, Wireless Service Engine (WLSE) is such
an appliance.

The High Availability is achieved via redundancy of 
appliances. This redundancy scheme is designed to support 
hardware or software failure of the appliances in a non-
disruptive manner. Redundancy is achieved by configuring
a cluster of two appliances with one common virtual IP 
address. The data is mirrored from the active appliance to 
the standby appliance at regular intervals.

One of the appliances is in active mode, performing all 
normal functions. The other appliance is in warm standby 
mode; that is, the appliance is up but no application
services are running. 

Both the active and standby appliances have their own IP 
addresses. The active appliance also owns the virtual IP 
address to which all the service requests are made.

The active appliance and standby appliance periodically poll
each other. If the standby appliance cannot reach the active
appliance, it will become the active appliance. This is 
called a switchover event. The switchover can be caused by 
other causes, for example, via user commands.

Both the active and standby appliances should implement 
this MIB and report any exceptions caused by switchover 
events.