Like all broker properties, cluster configuration properties can be set individually for each broker in a cluster, either in its instance configuration file (config.properties) or by using the -D option on the command line when you start the broker. However, except where noted in this chapter, each cluster configuration property must be set to the same value for each broker in a cluster.
For example, to specify the transport protocol for the cluster connection service, you can include the following property in the instance configuration file for each broker in the cluster: imq.cluster.transport=ssl. If you need to change the value of this property, you must change its value in the instance configuration file for every broker in the cluster.
For consistency and ease of maintenance, it is generally more convenient to collect all of the common cluster configuration properties into a central cluster configuration file that all of the individual brokers in a cluster reference. Using a cluster configuration file prevents the settings from getting out of synch and ensures that all brokers in a cluster use the same, consistent cluster configuration information.
A cluster configuration file can also include broker properties that are not used specifically for cluster configuration. For example, you can place any broker property in the cluster configuration file that has the same value for all brokers in a cluster. For more information, see Connecting Brokers into a Conventional Cluster