Wireless/Redundant Edge Services xl Module Management and Configuration Guide WS.02.xx and greater

10-7
Redundancy Groups
High Availability for Wireless Services
The number of licenses for the redundancy group equals the number of
licenses installed on the group member with the most licenses. For example,
a group includes these members:
■ one Wireless Edge Services xl Module with the default license (for 12 RPs)
and one additive license (for 12 RPs)
■ one Wireless Edge Services xl Module with the default license (for 12 RPs)
■ one Redundant Wireless Services xl Module
The redundancy group has two licenses and can adopt 24 RPs.
All members of the redundancy group share the group’s licenses. Any active
member can use the groups’ licenses to adopt an RP at any time. Any standby
member can use the groups’ licenses to adopt an RP in the circumstances
listed in “Adopting RPs in Standby Mode” on page 10-6.
Establishing a Redundancy Group
To ensure that each module recognizes that it is part of a redundancy group
and knows the IP address of the other modules in the group, you must
complete the steps to configure a redundancy group on each module. In
addition, you must ensure that the modules can communicate with one
another. For example, if the modules are installed in different wireless ser-
vices-enabled switches, the switches must be connected either directly or
indirectly (through one or more infrastructure switches).
When you configure and enable a redundancy group on a module, that module
begins the process of establishing a group. To successfully complete this
process, the module must receive communications from the other modules in
the redundancy group.
The process for establishing a redundancy group is the same for both primary
and redundant modules. If all modules all configured correctly as a redun-
dancy group, each will go through the following stages in establishing a group:
■ Startup state—The redundancy service starts on the module.
■ Discovery state—The module begins to send heartbeat messages to
advertise that it is available. It listens for the other modules to send
heartbeat messages to verify that its peers are also available.
In addition, the module sends an update message, listing the current
values for its redundancy group settings, such as heartbeat time,
discovery time, hold time, redundancy ID, and redundancy protocol
version. The other modules send an update message as well. The modules