HP-UX IPv6 Transition Mechanisms White Paper

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IPv4 host
IPv6/IPv4 host
IPv4 host
IPv4 host
IPv6/IPv4 host
IPv4 network
IP6-in-IP tunnel
IPv4 Router IPv4 Router
Figure 2: host-to-host tunnel configuration
5.2 Router-to-Router
In a router-to-router tunnel configuration, IPv6/IPv4 routers interconnected by an IPv4 infrastructure can
tunnel IPv6 packets between themselves. In this case, the tunnel spans one segment of the end-to-end
path the packet takes.
IPv4 network
IP6-in-IP tunnel
IPv6/IPv4 Router
IPv6/IPv4 Router
Figure 3: router-to-router tunnel configuration
IPv6 host
IPv6 host
IPv6 host
IPv6 host
IPv6 host
The router-to-router tunnel configuration is useful to connect two IPv6 domains separated by IPv4
network.
5.3 Host-to-Router and Router-to-Host
In a host-to-router configuration, the tunnel spans the first segment of the packet’s end-to-end path. In the
router-to-host configuration, the tunnel spans the last segment of the packet’s end-to-end path.
The host-to-router and router-to-host tunnel configuration is useful when a whole site needs access to a
service running on a dual stack host in an IPv4 network.