The following list summarizes the key points that were discussed in this chapter:
Supported CUCM deployment models are Single-Site (Campus), Multisite with Centralized Call Processing, Multisite with Distributed Call Processing, and Clustering over the IP WAN.
In the Single-Site deployment model, the CUCM, applications, and DSP resources are at the same physical location; all offsite calls are handled by the PSTN.
The Multisite with Centralized Call Processing model has a single CUCM cluster. Applications and DSP resources can be centralized or distributed. The IP WAN carries call-control signaling traffic, even for calls within a remote site.
The Multisite with Distributed Call Processing model has multiple independent sites, each with a CUCM cluster; the IP WAN carries traffic only for intersite calls.
Clustering over the WAN provides centralized administration, a unified dial plan, feature extension to all offices, and support for more remote phones during failover, but it places strict delay and bandwidth requirements on the WAN.
Clustering provide redundancy. A 1:1 redundancy design offers the highest availability but requires the most resources and is not as cost-effective as 2:1 redundancy.