Cisco Cisco Expressway Maintenance Manual
Clustering and Peers
This section describes how to set up a cluster of Expressway peers. Clustering is used to increase the capacity of
your Expressway deployment and to provide resiliency.
your Expressway deployment and to provide resiliency.
About Clusters
An Expressway can be part of a cluster of up to six Expressways. Each Expressway in the cluster is a peer of every
other Expressway in the cluster. When creating a cluster, you define a cluster name and nominate one peer as the
master from which all relevant configuration is replicated to the other peers in the cluster. Clusters are used to:
other Expressway in the cluster. When creating a cluster, you define a cluster name and nominate one peer as the
master from which all relevant configuration is replicated to the other peers in the cluster. Clusters are used to:
■
Increase the capacity of your Expressway deployment compared with a single Expressway.
■
Provide redundancy in the rare case that an Expressway becomes inaccessible (for example, due to a network
or power outage) or while it is in
or power outage) or while it is in
(for example, during a software upgrade).
About the configuration master
All peers in a cluster must have identical configuration for subzones, zones, links, pipes, authentication, bandwidth
control and Call Policy. To achieve this, you define a cluster name and nominate one peer as the configuration
master. Any configuration changes made to the master peer are then automatically replicated across all the other
peers in the cluster.
control and Call Policy. To achieve this, you define a cluster name and nominate one peer as the configuration
master. Any configuration changes made to the master peer are then automatically replicated across all the other
peers in the cluster.
You should only make configuration changes on the primary Expressway.
Caution:
Do not adjust any cluster-wide configuration until the cluster is stable with all peers running. Cluster
database replication will be negatively impacted if any peers are upgrading, restarting, or out of service when
you change the cluster's configuration.
you change the cluster's configuration.
Any changes made on other peers are not reflected across the cluster, and will be overwritten the next time the
primary’s configuration is replicated across the peers. The only exceptions to this are some
primary’s configuration is replicated across the peers. The only exceptions to this are some
You may need to wait up to one minute before changes are updated across all peers in the cluster.
Secure communication between peers
The Expressway uses IPsec (Internet Protocol Security) to enable secure communication between each cluster peer.
Authentication is carried out through the use of a pre-shared access key.
Authentication is carried out through the use of a pre-shared access key.
Each peer in the cluster must be individually configured with the IP address and associated access key of every other
peer in that cluster.
peer in that cluster.
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