This gave some clue http://www.jboss.org/file-access/default/members/jbossas/freezone/docs/Cl... Turns out, this configuration comes from a xml file JBOSS_HOME/server/all/deploy/cluster/jgroups-channelfactory.sar/META-INF/jgroups-channelfactory-stacks.xml : | <UDP | singleton_name="udp-async" | mcast_port="${jboss.jgroups.udp_async.mcast_port:45689}" | mcast_addr="${jboss.partition.udpGroup:228.11.11.11}" So based on this syntax, if the jboss.partition.udpGroup property is not set, then it defaults to 228.11.11.11. I guess, the code parsing this xml file should have taken care of setting this mcast_addr correctly. View the original post : http://www.jboss.org/index.html?module=bb&op=viewtopic&p=4230302#... Reply to the post : http://www.jboss.org/index.html?module=bb&op=posting&mode=reply&a...