Anycast-Another Communication Model for IP

Anycast is a new internetwork service, and a new feature of IPv6. Just like unicast and multicast, it’s a communication model for IP. With anycast service, a client can reach the most appropriate server, which is one of the servers that accept datagrams for the anycast address. Anycast has numerous potential applications, and is recognized as a useful service. However, many technological problems have limited its acceptance by the community. At present, anycast researchers focus on the routing protocol, stateless service, group management, LAN communications, address space, security, QoS, scalability etc. Some progress has been made. But, much work remains to be done. The protocols and standards for anycast are under the discussion, but have not reached a consensus. As a new service of next generation Internet, anycast offers a broad space to explore.