Choice of anycast and Anycast routing

Anycast (anycast) refers to the communication between some of the closest receivers in the topology structure of any sender in a group. In comparison, multicast refers to a single sender corresponding to a group of selected receivers of a communication, unicast refers to a single sender of a single receiver of a communication.
　　
Anycast is a method used to update routing tables in IPV6. When a host computer updates the routing table for a master group, first send data to the nearest host, IPV6 determines which gateway host is closest to and sends packets to the host, like unicast traffic, and then the host sends the message to its closest router, until all the routing tables in the group are updated.
　　
IPV6 supports three types of unicast (Unicast), multicast (multicast), and Anycast (anycast). There is no specific division of broadcast (broadcast) in IPv6, but as a typical type of multicast. The IPV6 contains three addresses that are associated with network devices: unicast, multicast, and anycast addresses. During routing, IPV6 does not differentiate between unicast and anycast addresses. In the reply packet header, the node that receives the Anycast packet needs to have its own unicast address as the sender address. AD and listening routing in anycast is done using Address Resolution Protocol (ARP) or link-level multicast. The process of forwarding packets in anycast is similar to unicast, and the last hop route selection process is similar to multicast.