ZXR10 5900E Series Configuration Guide (IPv6)
à
IPv6 address embedded with IPv4 address
In the RFC 2373, IPv6 provides two kinds of addresses.
One is the
IPv4-compatible address, which allows the IPv6 node to access IPv4 nodes
that do not support IPv6.. The other is the IPv4-mapping address, which
allows the IPv6 router to transmit IPv6 packets over the IPv4 network in the
tunnel mode, where the nodes understand both IPv4 and IPv6.
The high-order 80 bits of these two kinds of addresses are all set to zeros,
and the low-order 32 bits contain the IPv4 address. If the middle 16 bits of
an address are set to FFFF, it indicates that this address is the IPv6 address
mapping to IPv4 address. For the address structures of these two kinds of
addresses, refer to
.
Table 1-3 Structure of the IPv6 Address Embedded With IPv4 Address
IPv4 Compatible Address
80
16
32
0000.................................0000
0000
IPv4 address
IPv4 image address
80
16
32
0000.................................0000
FFFF
IPv4 address
RFC 4291 specifies that these addresses are not used in the IPv6 transition
mechanism. It is not required for new implementations to support the above
address structures.
l
Link Local Address and Site-Local Address
Using the network Model 10 address to translate IPv4 network addresses provides
an option for the institutions that do not want to apply for globally unique IPv4
network addresses.
A router that resides outside of an institution but used by the institution shall not
forward these addresses. It can neither prevent these addresses from being
forwarded, nor distinguish these addresses from other valid IPv4 addresses. It
is comparatively easier to make configurations for a router to enable it to forward
these addresses.
To realize this function, IPv6 allocates two different address segments from the
globally unique Internet space.
is originated from RFC 4291, indicating
the structures of link-local and site-local addresses. Site-local addresses were
originally designed to be used for addressing inside a site without the need for
a global prefix. The special behavior of this prefix is no longer supported in
new implementations (meaning that new implementations must treat this prefix as
Global Unicast). Existing implementations and deployments may continue using
this prefix.
1-6
SJ-20150114102049-011|2015-01-15 (R1.0)
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