The clustering configuration comes from the ClusterConfig element, not from anywhere in WLS. That element defines a JGroups protocol stack. See http://www.jgroups.org/javagroupsnew/docs/manual/html/index.html for general JGroups documentation. Each subelement within the stack defines a particular protocol. See pages linked from http://wiki.jboss.org/wiki/Wiki.jsp?page=JGroups for a discussion of what each protocol does and what the config options are. In brief, if you are using UDP, all servers on the network with the same mcast_addr and mcast_port config will see each other and form a group. If you are using TCP, you need to list your servers in the TCPPING protocol, or use the MPING protocol. View the original post : http://www.jboss.com/index.html?module=bb&op=viewtopic&p=3987654#... Reply to the post : http://www.jboss.com/index.html?module=bb&op=posting&mode=reply&a...