Used in: cluster-config.
Specifies the configuration information for the Multicast listener. This element is used to specify the address and port that a cluster will use for cluster wide and point-to-multipoint communications. All nodes in a cluster must use the same multicast address and port, whereas distinct clusters on the same network should use different multicast addresses.
By default Coherence uses a multicast protocol to discover other nodes when forming a cluster. If multicast networking is undesirable, or unavailable in your environment, the well-known-addresses feature may be used to eliminate the need for multicast traffic. If you are having difficulties in establishing a cluster via multicast, see the Multicast Test.
The following table describes the elements you can define within the multicast-listener element.
Element | Required/Optional | Description | ||
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<address> | Required | Specifies the multicast IP address that a Socket will listen or publish on.
Legal values are from 224.0.0.0 to 239.255.255.255. Default value depends on the release and build level and typically follows the convention of {build}.{major version}.{minor version}.{patch}. For example, for Coherence Release 2.2 build 255 it is 225.2.2.0. Preconfigured override is tangosol.coherence.clusteraddress |
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<port> | Required | Specifies the port that the Socket will listen or publish on.
Legal values are from 1 to 65535. Default value depends on the release and build level and typically follows the convention of {version}+{{{build}. For example, for Coherence Release 2.2 build 255 it is 22255. Preconfigured override is tangosol.coherence.clusterport |
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<time-to-live> | Required | Specifies the time-to-live setting for the multicast. This determines the maximum number of "hops" a packet may traverse, where a hop is measured as a traversal from one network segment to another via a router.
Legal values are from from 0 to 255.
Default value is 4.
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<packet-buffer> | Required | Specifies how many incoming packets the OS will be requested to buffer. | ||
<priority> | Required | Specifies a priority of the multicast listener execution thread.
Legal values are from 1 to 10. Default value is 8. |
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<join-timeout-milliseconds> | Required | Specifies the number of milliseconds that a new member will wait without finding any evidence of a cluster before starting its own cluster and electing itself as the senior cluster member.
Legal values are from 1 to 1000000. Note: For production use, the recommended value is 30000. Default value is 6000. |
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<multicast-threshold-percent> | Required | Specifies the threshold percentage value used to determine whether a packet will be sent via unicast or multicast. It is a percentage value and is in the range of 1% to 100%. In a cluster of "n" nodes, a particular node sending a packet to a set of other (i.e. not counting self) destination nodes of size "d" (in the range of 0 to n-1), the packet will be sent multicast if and only if the following both hold true:
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The content override attribute xml-override can be optionally used to fully or partially override the contents of this element with XML document that is external to the base document.