Information Technology Reference
In-Depth Information
Redundancy: CuCM groups and Device Pools
Two methods of configuring call-processing redundancy in Cisco CUCM deployments are CUCM groups and device pools. These
concepts are explored in this section.
Cisco CuCM groups
Cisco CUCM groups can specify a prioritized list of up to three CUCMs with which Cisco IP phones can register. It is possible for a
CUCM server to be in more than one group.
The operation of the CUCM group is straightforward: During initialization, Cisco IP phones download a configuration file from a
TFTP server, and this configuration file contains the prioritized list of CUCMs.
Cisco IP phones first attempt to register with the primary CUCM in the list, and if this fails, they attempt to register with the
secondary CUCM. Finally, they attempt to register with the tertiary CUCM.
During normal operation, if a CUCM fails, Cisco IP phones fail over to (reregister with) the secondary/tertiary CUCMs in the group.
Active calls are preserved, and Cisco IP phones reregister when existing calls are complete.
CUCM groups are associated with devices via a device pool. (Each device pool has an associated CUCM group, and each device is
associated with a device pool.)
You can configure CUCM groups with Cisco CUCM Administration by navigating to
System, Cisco Unified CM Group
.
Figure 1-3
shows the configuration of a CUCM group.
Note that the Auto-registration Cisco CUCM Group check box ensures that Cisco IP phones that autoregister receive the CUCM
group assignment shown. Only one CUCM group can be used for autoregistration per cluster.
If a CUCM group is associated with a device pool, or if a CUCM group is used for autoregistration, it cannot be deleted.
