To isolate you only have to change two: Partition Name - uniquely identifies membership group (see JGroups docs and/or Jboss admin guide) Multicast Address - IP JGroups will use to multicast (more info in JBoss admin guide) If those values are the same on two nodes that are on the same subnet, they will join into a cluster. If you only change Partition Name, the nodes will not join, however you'll be seeing an iritating message in your loggs telling you that some node is trying to join (becouse multicast IP is still the same), but refused. . . and so on View the original post : http://www.jboss.com/index.html?module=bb&op=viewtopic&p=3985035#... Reply to the post : http://www.jboss.com/index.html?module=bb&op=posting&mode=reply&a...