We get the same error. And this started out of the blue. It has been no problem for 3 months. The only solution is to either change the mcast IP or port. This is very severe - mostly because we don't know what is causing it. And not sure if the current production environment will be affected by it or not. Also, there are two places for mcast IP and Port specification - tc5-cluster-service.xml and cluster-service.xml. Does the IP and Port on these two should be ALWAYS same? If they can be different, what is the impact to keep them separate? Is it a good idea to provide different mcast IP AND Port for each environment (Production, UAT, DEV, developer specific). So as to avoid interference? How does one make sure that one environment does not affect the other in ANY way? This is causing some serious concerns. Please resolve. View the original post : http://www.jboss.com/index.html?module=bb&op=viewtopic&p=3971935#... Reply to the post : http://www.jboss.com/index.html?module=bb&op=posting&mode=reply&a...