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DES-7200 Configuration Guide Chapter 3 IPv6 Tunnel Configuration
3-3
By an ISATAP tunnel, the IPv4/IPv6 dual stack hosts on a same virtual link can
communicate one another inside the site.
On the ISATAP site, the ISATAP router provides standard router advertisement
message, allowing the ISATAP host to be automatically configured inside the site. At
the same time, the ISATAP router performs the function that an intra-site ISATAP host
and external IPv6 host forward messages.
The IPv6 address prefix used by ISATAP can be any legal 64-bit prefix for IPv6 unicast,
including the global address prefix, local link prefix and local site prefix. The IPv4
address is placed as the ending 32 bits of the IPv6 address, allowing a tunnel to be
automatically built.
It is very possible that ISATAP is used with other transition technologies.
z ISATAP interface identifier
The unicast address used by ISATAP is in the form of a 64-bit IPv6 prefix plus a 64-bit
interface identifier. The 64-bit interface identifier is generated in the revised EUI-64
address form. Where, the value of the first 32 bits of the interface identifier is
0000:5EFE, an interface identifier of ISATAP.
z ISATAP address structure
An ISATAP address refers to the unicast address containing an ISATAP interface
identifier in its interface identifier. An ISATAP address structure is shown in the
following figure:
The above figure shows that the interface identifier contains an IPv4 address. The
address is the IPv4 address of a dual stack host and will be used when an automatic
tunnel is automatically built.
For example, the IPv6 prefix is 2001::/64 and the embedded IPv4 address is
192.168.1.1. In the ISATAP address, the IPv4 address is denoted as the hexadecimal
numeral of C0A8:0101. Therefore, its corresponding ISATAP address is as follows:
2001::0000:5EFE:C0A8:0101