IP Version 6 Addressing Architecture，RFC4291
It includes the basic formats for the various types of IPv6 addresses (unicast, anycast, and multicast). There are no broadcast addresses in IPv6, their function being superseded by multicast addresses.
IPv6的地址分为单播、任播、多播，没有广播。——单播、任播、多播，是地址的类型type。
从范围scope上分，地址还分为全局的global和非全局的non-global，非全局的比如链路本地link local。Scope的定义在RFC4007.
In IPv6, all zeros and all ones are legal values for any field, unless specifically excluded. Specifically, prefixes may contain, or end with, zero-valued fields.
在IPv6中，全0和全1的值是合法的，而在IPv4中，全0表示本网，全1表示广播。
IPv6 addresses of all types are assigned to interfaces, not nodes. An IPv6 unicast address refers to a single interface. Since each interface belongs to a single node, any of that node's interfaces' unicast addresses may be used as an identifier for the node.
所有的IPv6地址都是赋给接口的，不是赋给节点的。由于任何接口都属于单个节点，因此，节点的任意接口的单播地址都可以用作节点的标识符（地址）。
Unicast addresses with a scope greater than link-scope are not needed for interfaces that are not used as the origin or destination of any IPv6 packets to or from non-neighbors. This is sometimes convenient for point-to-point interfaces.
比链路本地范围大的单播地址，对于不与非邻居交互IPv6数据报的接口，是不需要的。比如，路由协议，所有的数据报都只在链路上传递，因此，也是不需要比链路本地大的单播地址的，是这样吗？
0:0:0:0:0:0:0:1 the loopback address
这是回环地址。