HP-UX IPv6 Transition Mechanisms White Paper

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Within the 6to4 site, the 6to4 router advertises the 6to4 prefix derived from its global IPv4 address. The
6to4 hosts in the site autoconfigure IPv6 addresses using the advertised 6to4 prefix and create a default
route to the advertising 6to4 router. The 6to4 hosts within the 6to4 site communicate using IPv6 routing
protocols.
IPv6 communication with 6to4 hosts in a different 6to4 site is sent to the 6to4 router using the default
route. The 6to4 router will encapsulate the IPv6 packets in an IPv4 header. The IPv4 source address will
be the IPv4 address of the 6to4 router and the destination IPv4 address will be the IPv4 address
embedded in the destination 6to4 IPv6 address. The encapsulated packet will be sent to the destination
6to4 router using IPv4 routing infrastructure. The destination 6to4 router will decapsulate the packet and
will forward the IPv6 packet to its final destination.
In case of communication with native IPv6 hosts, the 6to4 router will send the encapsulated packet to the
6to4 relay router using its default route pointing to the 6to4 relay router.
7. Transition from IPv4 to IPv6
To prepare for a transition from IPv4 to IPv6, the following steps are recommended:
• Develop IP-version independent applications: Existing and new applications should be made
protocol independent without specific dependencies on either IPv4 or IPv6. The applications should
use version independent data structures and version independent APIs as specified in [2].
• Upgrade the DNS Infrastructure in the organization: IPv6 addresses are stored in DNS using the
new record type AAAA. The DNS infrastructure must be upgraded to support AAAA records along
with the support for A records.
• Upgrade hosts to dual stack: Hosts must be upgraded to dual stack. This allows the hosts to support
both existing IPv4 applications and new version independent applications.
• Upgrade routers to dual stack: Routers must be upgraded to dual stack to support IPv6 routing and
transition mechanisms.