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Configure clusters

Before you begin

Ensure that you have created a cluster and Managed Servers. For information on creating a Managed Server, see Create Managed Servers.

If you are configuring a new cluster in a new domain, Oracle recommends that you use the Configuration Wizard. For more information on creating a clustered domain, see Setting Up WebLogic Clusters in Administering Clusters for Oracle WebLogic Server.

For information on selecting a messaging mode (unicast or multicast) for your cluster, see Communications in a Cluster.

To perform basic cluster configuration:

  1. If you have not already done so, in the Change Center of the Administration Console, click Lock & Edit (see Use the Change Center).
  2. In the left pane of the Console, select Environment > Clusters.

    The Summary of Clusters table displays all the clusters defined in the domain.

  3. In the Clusters table, select the cluster you want to configure.
  4. Select Configuration > General.
    1. In Default Load Algorithm, define the algorithm to use for load balancing between replicated services.

      For more information, see Load Balancing in a Cluster.

    2. In Cluster Address, enter the address that forms a portion of the URL that a client uses to connect to this cluster.
    3. If you do not explicitly set the cluster address, in Number of Servers in Cluster Address, update the number of server instances to be listed from the cluster when generating the cluster address automatically.
    4. Optionally, in Enable Transaction Affinity, you can enable transaction affinity to allow server instances that are participating in the global transaction to be chosen while servicing clustered requests.
    5. Optionally, select Enable Concurrent Single Activation to specify whether to allow the concurrent activation, deactivation, or restart of two or more singleton services.
    6. Optionally, expand Advanced to define advanced settings for this cluster.
  5. Select Configuration > Messaging.
    1. In Messaging Mode, select the messaging mode you want to use for this cluster.

      If you are creating a cluster within an existing WebLogic Server environment or you need to ensure backward compatibility with older versions of WebLogic Server, you must use the multicast messaging type. IP multicast is a simple broadcast technology that enables multiple applications to subscribe to a given IP address and port number and listen for messages.

    2. If you are using the unicast messaging mode, enter the unicast broadcast channel in Unicast Broadcast Channel. This channel is used to transmit messages within the cluster. If you do not specify a channel, the default channel is used.

      Note: For a custom unicast broadcast channel, the outbound-enabled attribute must be set to true. See Configure custom network channels.

    3. If you are using the multicast message mode:

      Enter the multicast address of the new dynamic cluster in Multicast Address. A multicast address is an IP address in the range from to The default value used by WebLogic Server is This address must be unique to this cluster and should not be shared by other applications.

      Enter the multicast port for the new dynamic cluster in Multicast Port. The multicast port is used by cluster members to communicate with each other. Valid values are between 1 and 65535.

    4. Optionally, expand Advanced to define advanced messaging settings for this cluster.
  6. Click Save.
  7. For more advanced configuration options, see the following topics:
  8. To activate these changes, in the Change Center of the Administration Console, click Activate Changes.
    Not all changes take effect immediately—some require a restart (see Use the Change Center).

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