CallManager Clustering
.. Cisco AVVID infrastructure includes a variety of features to facilitate
load balancing, scalability, and redundancy for IP telephony and
multimedia conference solutions.
.. Cisco CallManager clusters are used to improve the scalability and
reliability of Cisco IP telephony solutions.
.. Multipoint Control Unit cascading is used to improve the scalability of
voice/video conferencing.
.. A maximum of eight Cisco CallManagers can be members of a cluster,
with as many as six used for call processing.
.. The possible roles of servers within a cluster are: database publisher
server,TFTP server, application server, primary call-processing server,
and backup call-processing server.
.. Intra-cluster communications rely on high-speed network connections,
and are not supported across WANs.
.. The CallManager database contains the configuration of all IP telephony
devices.
.. Real-time data replicated between servers in a cluster consists of
registration information of IP telephony devices.
www.syngress.com
AVVID Clustering • Chapter 4 127
.. Many CallManager features do not function between different clusters.
.. Database redundancy is achieved by replicating the publisher database to
all servers within a cluster.
.. Redundancy groups facilitate server failover. A device is associated with
a redundancy group, which is a list of up to three servers. If the primary
server fails, call processing is transferred to the secondary server.
.. Balanced call processing can be achieved by assigning different primary
servers to different groups of devices.
.. Device weights are used to calculate the maximum number of devices
that can be supported by a single CallManager server.