Copyright (C) 2000-2012 |
Whole document tree 3.1. Addresses without a special prefix3.1.1. Localhost addressThis is a special address for the loopback interface, similiar to IPv4 with its "127.0.0.1". With IPv6, the localhost address is:
or compressed:
Packets with this address as source or destination should never leave the sending host. 3.1.2. Unspecified addressThis is a special address like "any" or "0.0.0.0" in IPv4 . For IPv6 it's:
or:
These addresses are mostly used/seen in socket binding (to any IPv6 address) or routing tables. Note: the unspecified address cannot be used as destination address. 3.1.3. IPv6 address with embedded IPv4 addressThere are two addresses which contain an IPv4 address. 3.1.3.1. IPv4-mapped IPv6 addressIPv4-only IPv6-compatible addresses are sometimes used/shown for sockets created by an IPv6-enabled daemon, but only binding to an IPv4 address. These addresses are defined with a special prefix of length 96 (a.b.c.d is the IPv4 address):
or in compressed format
For example, the IPv4 address 1.2.3.4 looks like this:
3.1.3.2. IPv4-compatible IPv6 addressAlso for sockets, in this case it is for a dual purpose and looks like:
or in compressed format
These addresses are also used by automatic tunneling, which is being replaced by 6to4 tunneling. |