Note that multicast loopback is not changed by JGroups - by default it is *enabled* in the OS, so setting IP_MULTICAST_LOOP is superfluous. I don't understand the other argument: do you want to the OS to pick the NIC, or do you want to set it youself ? If you want to ignore the interface defined by JBoss through -b, then set system property jgroups.ignore.bind_addr to true View the original post : http://www.jboss.com/index.html?module=bb&op=viewtopic&p=4102223#... Reply to the post : http://www.jboss.com/index.html?module=bb&op=posting&mode=reply&a...