On 05/05/2017 03:09 PM, Sergei Gerasenko wrote: > Hi, > > I have a very simple question. > > Pacemaker uses a dedicated "multicast" interface for the totem protocol. > I'm using pacemaker with LVS to provide HA load balancing. LVS uses > multicast interfaces to sync the status of TCP connections if a failover > occurs. > > I can understand services using the same interface if ports are used. > That way you can get a socket (ip + port). But there's no ports in this > case. So how can two services exchange messages without specifying > ports? I guess that's somehow related to multicast, but how exactly I > don't get. > > Can somebody point me to a primer on this topic? > > Thanks, > S.
Corosync is actually the cluster component that can use multicast, and it does use a specific port on a specific address. By default, it uses ports 5404 and 5405 when using multicast. See the corosync.conf(5) man page for mcastaddr and mcastport. Also see the transport option; corosync can be configured to use UDP unicast rather than multicast. I don't remember much about LVS, but I would guess it's the same -- it's probably just using a default port if not specified in the config. _______________________________________________ Users mailing list: Users@clusterlabs.org http://lists.clusterlabs.org/mailman/listinfo/users Project Home: http://www.clusterlabs.org Getting started: http://www.clusterlabs.org/doc/Cluster_from_Scratch.pdf Bugs: http://bugs.clusterlabs.org