Cisco CallManager Redundancy
Device Pool
Primary
Secondary
Tertiary
IP telephones, and other IP telephony devices such as gateways, transcoders,
conference bridges, and voice mail ports can be assigned to a device pool.A device
pool is defined as a group of IP telephony devices that share the same characteristics.
These characteristics are defined when the device pool is created, and include
name, region, media resource group list, user hold Music On Hold source, autoanswer
feature control, and most importantly the associated Cisco CallManager
group.As with CallManager groups, each device within a pool should share a similar
characteristic, such as geographical location, or logical subnet.
IP phones within a pool maintain a TCP connection with both the primary
and secondary CallManager servers in the CallManager group associated with
that pool.This facilitates immediate failover should the primary CallManager
server fail.