Cisco Unified Communications Manager System Guide, Release 6.1(1)
Clustering
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Clustering

Table Of Contents

Clustering

Clusters

Intercluster Communication

Balanced Call Processing

Cluster Configuration Checklist

Where to Find More Information


Clustering


The clustering feature of Cisco Unified Communications Manager provides a mechanism for seamlessly distributing call processing across the infrastructure of a converged IP network. Clustering provides transparent sharing of resources and features and enables system scalability.

This section covers the following topics:

Clusters

Intercluster Communication

Balanced Call Processing

Cluster Configuration Checklist

Where to Find More Information

Clusters

A cluster comprises a set of Cisco Unified Communications Manager servers that share the same database and resources. You can configure the servers in a cluster in various ways to perform the following functions:

Database server (only one database server in the cluster)

TFTP server

Application software server

Before you install the Cisco Unified Communications Manager software on subsequent servers, you must define the nodes in Server Configuration in Cisco Unified Communications Manager Administration.

Using the Service Activation window in the Cisco Unified Serviceability application, you can specify which server performs which function for the cluster. You can dedicate a particular server to one function or combine several functions on one server, depending on the size of your system and the level of redundancy that you want.

Each cluster can have only one database server (first node) and usually one TFTP server (either separate or combined).


Tip The Restart Cisco Communications Manager on Initialization Exception service parameter determines whether the Cisco CallManager service restarts if an error occurs during initialization. This parameter defaults to TRUE and, with this value, the Cisco Communications Manager initialization aborts when an error occurs during initialization. Setting the value to FALSE allows initialization to continue when an error is encountered. You can locate this clusterwide parameter in the System - General subsection. Refer to "Service Parameters Configuration" in the Cisco Unified Communications Manager Administration Guide for detailed information on configuring service parameters.


For details on cluster size and recommended configurations, refer to Cisco Unified Communications Solution Reference Network Design (SRND).

For details of the Service Activation window, refer to the Cisco Unified Serviceability Administration Guide.

Intercluster Communication

In very large environments, you might need to configure more than one cluster to handle the call-processing load. Communication between the clusters typically occurs by means of intercluster trunks or gatekeeper trunks. Most large systems use one of two main types of multicluster configurations:

Large, single campus, or metropolitan-area network (MAN)

Multisite WAN with distributed call processing (one or more Cisco Unified Communications Managers at each site)

Because intercluster trunks in a MAN usually have sufficient bandwidth, they do not require any call admission control mechanism. Multisite WANs with distributed call processing typically use gatekeeper technology for call admission control.

Intracluster Communication

Cisco Unified Communications Manager also supports intracluster communication, which is a multisite WAN with centralized call processing (no Cisco Unified Communications Manager at the remote site or sites). Multisite WANs with centralized call processing use the locations feature in Cisco Unified Communications Manager to implement call admission control.

Most features of Cisco Unified Communications Manager do not extend beyond a single cluster, but the following features do exist between clusters:

Basic call setup

G.711 and G.729 calls

Multiparty conference

Call hold

Call transfer

Call park

Calling line ID

For more information about intercluster communication and call admission control, refer to Cisco Unified Communications Solution Reference Network Design (SRND).

Balanced Call Processing

After installing the Cisco Unified Communications Managers that form a cluster, you should, as much as possible, evenly balance the call-processing load across the system by distributing the devices (such as phones, gateways, CTI route points, CTI ports, and route lists) among the various Cisco Unified Communications Managers in the cluster. To distribute the devices, you configure Cisco Unified Communications Manager groups and device pools and then assign the devices to the device pools in a way that achieves the balance that you want.

Cisco Unified Communications Manager groups and device pools represent logical groupings of devices that you can arrange in any way that you want. For ease of administration, make sure that all the devices in a group or pool share a common and easily identified characteristic, such as their physical location on the network.

You can also use Cisco Unified Communications Manager groups to establish redundancy (backup call processors) for the primary Cisco Unified Communications Manager in the group. A Cisco Unified Communications Manager group comprises an ordered list of up to three Cisco Unified Communications Manager servers. During normal operation, the first (primary) Cisco Unified Communications Manager in the group controls all device pools and devices that are assigned to that group. If the primary Cisco Unified Communications Manager in a group fails, control of the device pools and devices that are registered with the primary Cisco Unified Communications Manager transfers to the next Cisco Unified Communications Manager in the group list.

For example, assume a simplified system that comprises three Cisco Unified Communications Managers in a cluster, with 300 existing Cisco Unified IP Phones and provisions to auto-register new phones as they are added later.

The configuration includes four Cisco Unified Communications Manager groups: group G1 that is assigned to device pool DP1, group G2 that is assigned to device pool DP2, group G3 that is assigned to device pool DP3, and group G4 that is assigned to device pool DP4. Group G4 serves as the default group for devices that auto-register.

Unified CM1 serves as the primary Cisco Unified Communications Manager for the devices in DP1 and DP2, first backup for DP3, and second backup for the devices in DP4.

Unified CM2 serves as the primary Cisco Unified Communications Manager for the devices in DP3 and DP4, first backup for DP1, and second backup for the devices in DP4.

Unified CM3 serves as the first backup Cisco Unified Communications Manager for the devices in DP2 and DP4 and second backup for the devices in DP1 and DP3.

Cluster Configuration Checklist

Table 6-1 provides an overview of the steps that are required to install and configure a Cisco Unified Communications Manager cluster.

Table 6-1 Cluster Configuration Checklist 

Configuration Steps
Procedures and Related Topics

Step 1 

Install the database server (first node).

Refer to the installation documentation for the hardware components that you are installing.

Step 2 

Gather the information that you need to install Cisco Unified Communications Manager and any other software applications on the first node and subsequent servers. Also, determine how you will allocate the servers in the cluster.

Cisco Unified Communications Solution Reference Network Design (SRND)

Installing Cisco Unified Communications Manager Release 6.1(1)

Cisco Unified IP-IVR Installation Guide

Step 3 

Install Cisco Unified Communications Manager and any additional software applications on the subsequent servers.


Note Before installing the subsequent servers, you must define the nodes in Server Configuration in Cisco Unified Communications Manager Administration.


Installing Cisco Unified Communications Manager Release 6.1(1)

Cisco Unified IP-IVR Installation Guide

Server Configuration, Cisco Unified Communications Manager Administration Guide

Step 4 

Configure device pools and use them to assign specific devices to a Cisco Unified Communications Manager group.

Device Pool Configuration, Cisco Unified Communications Manager Administration Guide

Step 5 

If you are using an intercluster trunk, install and configure it as an intercluster trunk, either gatekeeper-controlled or non-gatekeeper-controlled.

Cisco Unified Communications Solution Reference Network Design (SRND)

Configuring a Trunk, Cisco Unified Communications Manager Administration Guide

Trunk Configuration Settings, Cisco Unified Communications Manager Administration Guide

Step 6 

If you want to provide call admission control for an intercluster trunk, configure either a gatekeeper-controlled intercluster trunk or Cisco Unified Communications Manager locations.

Cisco Unified Communications Solution Reference Network Design (SRND)

Trunk Configuration, Cisco Unified Communications Manager Administration Guide

Location Configuration, Cisco Unified Communications Manager Administration Guide

Where to Find More Information

Related Topics

Cisco Unified Communications Manager Group Configuration, Cisco Unified Communications Manager Administration Guide

Device Pool Configuration, Cisco Unified Communications Manager Administration Guide

Trunk Configuration, Cisco Unified Communications Manager Administration Guide

Location Configuration, Cisco Unified Communications Manager Administration Guide

Additional Cisco Documentation

Cisco Unified Communications Solution Reference Network Design (SRND)

Installing Cisco Unified Communications Manager Release 6.1(1)

Cisco Unified IP-IVR Installation Guide

Cisco Unified Serviceability Administration Guide