Support is also provided for a connection, or routing step, to be established to the `nearest' (in routing terms) of a cluster of nodes. Addresses which end in all zero bits represent the cluster of nodes with any value in these bits. Partial source direct routing can be supported using cluster addresses. Partial source direct routing could be used to select one of a number of carriers without specifying which carrier router to use.
Multicast addresses begin with prefix 1111 1111. The next 8 bits specify whether the multicast is to a permanent assigned multicast group or to a transient group and whether the scope is within the node, the network link, the site, the organisation, the local `community' or global. Permanently assigned multicast addresses are allocated to all nodes, hosts, and routers for both the intra-node and intra-link scopes. Multicasts replace IPv4 broadcasts.
An address class has been allocated for geographic addresses but as yet the way this is to be used has not been agreed on.