User Guide

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AsyncOS 9.1.2 for Cisco Email Security Appliances User Guide

Chapter 39 Centralized Management Using Clusters

Cluster Requirements

• Machines in a cluster must have resolvable hostnames in DNS. Alternatively, you can use IP

addresses instead, but you may not mix the two.

See DNS and Hostname Resolution, page 39-18. Cluster communication is normally initiated using

the DNS hostnames of the machines.

• A cluster must consist entirely of machines running the same version of AsyncOS.

See Upgrading Machines in a Cluster, page 39-12 for how to upgrade members of a cluster.

• Machines can either join the cluster via SSH (typically on port 22) or via the Cluster Communication

Service (CCS).

See Cluster Communication, page 39-18.

• Once machines have joined the cluster, they can communicate via SSH or via Cluster

Communication Service. The port used in configurable. SSH is typically enabled on port 22, and by

default CCS is on port 2222, but you can configure either of these services on a different port.

In addition to the normal firewall ports that must be opened for the appliance, clustered machines

communicating via CCS must be able to connect with each other via the CCS port. See Cluster

Communication, page 39-18.

• You must use the Command Line Interface (CLI) command clusterconfig to create, join, or

configure clusters of machines.

Once you have created a cluster, you can manage non-cluster configuration settings from either the

GUI or the CLI.

See Creating and Joining a Cluster, page 39-4 and Administering a Cluster from the GUI,

page 39-15.

Cluster Organization

Within a cluster, configuration information is divided into 3 groupings or levels. The top level describes

cluster settings; the middle level describes group settings; and the lowest level describes

machine-specific settings.