IPv6 RFC 4291 协议摘录-IP Version 6 Addressing Architecture

IPv6的地址分为以下几类：

Unicast:   An identifier for a single interface.  A packet sent to a unicast address is delivered to the interface identified by that address.

Anycast:   An identifier for a set of interfaces (typically belonging to different nodes).  A packet sent to an anycast address is delivered to one of the interfaces identified by that address (the "nearest" one, according to the routing protocols' measure of distance).

Multicast: An identifier for a set of interfaces (typically belonging to different nodes).  A packet sent to a multicast address is delivered to all interfaces identified by that address.