Cisco Unified CallManager Clustering and Deployment Options

This chapter covers the following topics:

• The concepts and design strategies behind a Cisco Unified CallManager cluster
• The types of replication that occur in a Cisco Unified CallManager cluster
• Properly designing the Cisco Unified CallManager cluster for redundancy
• The four Cisco Unified CallManager deployment models

Legacy PBX systems have quite the reputation for reliability. As a general track record, PBXs provide an uptime of 99.999 percent (known as the "five-nines" of reliability). This translates to an unbelievable 5.3 minutes of downtime per year! To match this standard of reliability, multiple Cisco CallManager servers are grouped into a cluster. Most administrators recognize the term "cluster" as an ability to allow multiple servers to act as one device, which is the type of clustering provided by Windows clustering services. The Cisco CallManager cluster operates quite differently.

After you understand the clustered relationship of Cisco CallManager, you can plan your deployment strategy using the four deployment models provided by Cisco CallManager. This chapter discusses the cluster relationship and deployment options provided by the Cisco CallManager and the options available to enterprises to deploy a highly available IP telephony network.