"By default, the Enterprise Platform binds to all networking addresses at start-up"
==> The default is a 127.0.0.1 binding
"-u optional, otherwise TCP"
==> if -u not given multicast will be used with the default address 230.0.0.4

http://docs.redhat.com/docs/en-US/JBoss_Enterprise_Application_Platform/5/html/Administration_And_Configuration_Guide/ch03.html