(We discussed offline; following is for other interested people). Issue is the multiplexer-stacks.xml file is read and parsed by JGroups directly, bypassing the AS deployer code that does the substitution. Plus, there's nothing AS specific about system property substitution; seems like a useful feature for JGroups outside the AS. Created a JIRA: http://jira.jboss.com/jira/browse/JGRP-272 View the original post : http://www.jboss.com/index.html?module=bb&op=viewtopic&p=3965026#... Reply to the post : http://www.jboss.com/index.html?module=bb&op=posting&mode=reply&a...