Dear Tim, maybe you can do an "independent" check using the JGroups lib stand-alone, which offers two sets of a cluster demo. This may help to narrow down the issue to the Tomcat setup or the "other" (OS or network configuration) areas.
Please refer to http://www.jgroups.org/tutorial-3.x/html_single/ , section "1.4. Running a Demo Program" You just need the lib and a JVM, i.e. you can use it out of the box at your Tomcat machines. The "Draw Demo" requires Graphics, but you also may use another Testcase offering a textmode receiver and sender. You may start this receivers on every machine and then one or more senders on demand. On both demo's, cluster status messages are displayed on stdout. Here my somewhat older starter scripts: root@genless /opt/jgroups # cat _receiver ( cd `dirname $0` || exit 1 java -cp jgroups.jar org.jgroups.tests.McastReceiverTest -mcast_addr 224.10.10.10 -port 5555 $@ ) root@genless /opt/jgroups # cat _sender ( cd `dirname $0` || exit 1 java -cp jgroups.jar org.jgroups.tests.McastSenderTest -mcast_addr 224.10.10.10 -port 5555 $@ ) root@genless /opt/jgroups # cat _draw-demo ( cd `dirname $0` || exit 1 java -Djava.net.preferIPv4Stack=true -cp jgroups.jar org.jgroups.demos.Draw $@ ) root@genless /opt/jgroups # tree . |-- _draw-demo |-- _receiver |-- _sender |-- _src | |-- jgroups-2.9.0.GA.jar | `-- jgroups-3.0.10.Final.jar `-- jgroups.jar -> _src/jgroups-3.0.10.Final.jar Yours Guido
