3. Site-level Local Addresses
The format of the site-level local addresses is shown as follows:
| 10 |
| bits | 38 bits | 16 bits | 64 bits |
+-------------+----------------+--------------+---------------------------------------+
|1111111011| 0 | subnet ID | interface ID |
+-------------+---------------+-------------+-----------------------------------------+
The site-level local address can be taken to transmit the data within the site, and the router
will not forward the message of the source address of the destination address with the
site-level local address to Internet. Namely, such packet route can only be forwarded within
the site, but cannot be forwarded to out of the site. The former 10-bit prefix of the site-level
local address is slightly different of that of the link-level local address, whose intermediate 38
bits are 0, the subnet identifier of the site-level local address is 16 bits, while the latter 64 bits
also indicates the interface identifier, usually for the EUI-64 address of IEEE.
4. IPv4 Addresses-embedded IPv6 Addresses
The RFC2373 also defines 2 types of special IPv6 addresses embedded with IPv4
addresses:
IPv4-compatible IPv6 address
| 80 bits | 16 | 32 bits |
+-----------------------------------------------------+----+----------------------------+
|0000.....................................................0000|0000| IPv4 address |
+------------------------------------------------------+----+---------------------------+
IPv4-mapped IPv6 address
| 80 bits | 16 | 32 bits |
+-----------------------------------------------------+----+---------------------------+
|0000........................................................0000|ffff| IPv4 address |
+-----------------------------------------------------+----+---------------------------+
The IPv4-compatible IPv6 address is mainly used to the automatic tunneling, which supports
both the IPv4 and IPv6. The IPv4-compatible IPv6 address will transmit the IPv6 message
via the IPv4 router in the tunneling way. The IPv6 address of an IPv4 mapping is used to
access the nodes that only support IPv4 by IP6 nodes. For example, when one IPv6
application of the IPv4/IPv6 host requests the resolution of a host name (the host only
supports IPv4), the name server will internally generate the IPv6 addresses of the IPv4
mapping dynamically and return them to the IPv6 application.
32.1.2.2 Multicast Addresses
The format of the IPv6 multicast address is shown as follows:
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