Anycast is also used as an addressing method in IP networks. With anycast addressing, the computer that is topologically closest is addressed in a group of computers. Only the region in which the computer group is located is specified in the addressing. The computer or node that is reached fastest responds. With this addressing type the fastest reachable computer of a computer group can be addressed.
The term anycast stands in contrast to multicast where a group of receiving stations can be addressed with one sending station, and in contrast to unicast where a sending station is connected to a single receiving station.
Anycast addressing is particularly suitable for updating the routing tables of a host group. IPv6 determines the closest router and sends it the data packets, just as with unicast. The addressed router continues to send the data packets in anycast until all routing tables have been updated. The anycast addressing of IPv6 is described in RFC 2373.