TCP definitely doesn't scale as well as UDP multicast. But whether that is a real issue depends on what kind of traffic you have between the nodes. The services that generate a lot of traffic over the JGroups channels are 1) HttpSession replication 2) EJB StatefulSessionBean replication 3) Hibernate/JPA entity caching. 1) and 2) can be made highly scalable by using buddy replication. 3) is more complex, but there are things you can do as well (use INVALIDATION_SYNC, don't cache query result sets, don't cache entities that are frequently updated.) View the original post : http://www.jboss.org/index.html?module=bb&op=viewtopic&p=4237752#... Reply to the post : http://www.jboss.org/index.html?module=bb&op=posting&mode=reply&a...