Communication between clusters of processing nodes is initiated by designating a link layer address and a target node name in a remote cluster. The link layer address is transmitted to the target node via a regular network transmission. The link layer address is stored locally in each cluster and the nodes in each cluster are signaled that a configuration change has been made, so that gateway nodes in the clusters can obtain the link layer address to use for subsequent communications with the other cluster, such as event notifications of node status changes.