Wolfgang, you can't arbitrarily ping multicast addresses as they don't really exist in the sense that an ethernet interface exists as a card. Multicast is a "subscription" based concept. You have to be listening for multicast traffic to receive it at all. To "listen", one "joins" a multicast group (bind to a mcast ip address) and the router, if configured properly will route mcast traffic to your interface. There are certain mcast addresses you should never use explicitly. As mentioned, 224.0.0.1 is one of them, there are others but I can't recall what they are. Your other config didn't work (with respet to multicast) because all of your nodes were listening to different multicast "groups" which is like trying to dial in on a party line, but everone using the wrong phone number. Important to reitterate, Multicast has to be configured by whoever runs your router(s). If Multicast is not enabled on a switch, even if it is on your network, it turns in to broadcast on that switch, which defeats the purpose of multicast in the first place. Hope this clears some multicast stuff up for you. -----Original Message----- From: linux-cluster-bounces@xxxxxxxxxx [mailto:linux-cluster-bounces@xxxxxxxxxx] On Behalf Of Wolfgang Pauli Sent: Wednesday, April 26, 2006 8:46 PM To: sdake@xxxxxxxxxx; linux clustering Subject: Re: multicast howto 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 -- Linux-cluster@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/linux-cluster
