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In order for Apache Ignite to form a multinode cluster the nodes need to know about eachother. This can be achieved using ip multicast. The class to do this in Ignite is TcpDiscoveryMulticastIpFinder which has property "mulitcastGroup" which is in effect a tcp/ip multicast address that will be used by nodes on the cluster to discover eachother. If one uses TcpDiscoveryMulticastIpFinder without specifying a multicast group it will use a default of 228.1.2.4 shown in the code snippet below:

public class TcpDiscoveryMulticastIpFinder extends TcpDiscoveryVmIpFinder {
    /** Default multicast IP address (value is {@code 228.1.2.4}). */
    public static final String DFLT_MCAST_GROUP = "228.1.2.4";

    //code ommitted ...

}

However, the IPv4 specification for multicast, indicates that one should use multicast addresses in the range 239.0.0.0-239.255.255.255 for locally administered ad-hoc purposes. The specification does not explicitly define what to do with multicast addresses starting with 228. Is there any special reason that Apache Ignite uses 228.1.2.4 or is this an incidental choice rather than a delirate one. Should I use the default group or should I prefer one in the 239.0.0.0-239.255.255.255 range???

murungu
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1 Answers1

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I don't think that there was any special reason for that. I could not find something related to that at dev/user lists, and git repository. I think you can use any suitable multicast address.

sk0x50
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