Ok that was easy. I have changed the ServiceContainer "all" config to not start the multiplexer. What's interesting is that yesterday after my wireformat refactoring pretty much all the clustering tests were failing. After turning off the multiplexer they now pass :) I can only assume the jgroups stack config the multiplexer was using were incorrect. We *really* need to get these in one place, so core test, jms tests and multiplxer all use the same stacks, otherwise this is a config nightmare. View the original post : http://www.jboss.com/index.html?module=bb&op=viewtopic&p=4009288#... Reply to the post : http://www.jboss.com/index.html?module=bb&op=posting&mode=reply&a...