Thanks! First, I had to figure out how multicast works. Still don't fully understand it. I can ping 224.0.0.1 and I get responses from all hosts in the same subnet. It tried to ping 225.0.0.8 but that does not really work. But I don't know whether it has to. I have changed the cluster.conf to have only two nodes. Just to get the basic understanding. I have node dream on subnet 210 and neo on 223. They still form their own clusters. Should I just try different addresses, or do the switches/routers have to be programmed for that? regards, wolfgang <?xml version="1.0" ?> <cluster config_version="2" name="alpha_cluster"> <fence_daemon post_fail_delay="0" post_join_delay="3"/> <clusternodes> <clusternode name="dream" votes="1"> <multicast addr="225.0.0.9" interface="eth0"/> <fence> <method name="1"> <device name="human" nodename="dream"/> </method> </fence> </clusternode> <clusternode name="neo" votes="1"> <multicast addr="225.0.0.9" interface="eth0"/> <fence> <method name="1"> <device name="human" nodename="neo"/> </method> </fence> </clusternode> </clusternodes> <cman expected_votes="1" two_node="1"> <multicast addr="225.0.0.9"/> </cman> <fencedevices> <fencedevice agent="fence_manual" name="human"/> </fencedevices> <rm> <failoverdomains/> <resources/> </rm> </cluster> -- Linux-cluster@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/linux-cluster