High availability communications require the system to work reliably with pre-existing transport infrastructures and to integrate with a wide variety of external connectivity options. As a result, the underlying architecture must be designed to support reliable performance at every level. Communication Manager uses a variety of techniques to achieve this high reliability and availability.

Communication Manager automatically and continually assesses performance, and detects and corrects errors as they occur. The software incorporates component to subassembly self-tests, error detection and correction, system recovery, and alarm escalation paths. The maintenance subsystem of Communication Manager manages hardware operation, software processes, and data relationships.

Servers running the duplex template provide server redundancy, with call preserving failover, on the strength of the Linux operating system.

For more information about availability assessment and methodologies, see:

• The white paper, Avaya Communication Manager Software Based Platforms: High Availability Solutions, Avaya Aura® Media Servers and Gateways, available on the Avaya Support website, https://support.avaya.com.

• The white paper, Building Survivable VoIP for the Enterprise, available on the Tolly Group website https://tolly.com.

Communication Manager availability consists of providing a duplicated server pair that can be collocated or separated. These servers contain the same system and data files and work in an active/standby mode. When the active server fails, the servers interchange roles, and the standby server becomes the active server.

Collocated servers are generally in the same rack in the same room and connected by a crossover cable or through customer LAN using software duplication. With server separation, the two servers can be geographically separated. Server separation offers an improved survivability option by allowing the servers to reside in two different buildings across a campus or a small Metropolitan Area Network.