R0106-HP MSR Router Series Layer 3 - IP Services Configuration Guide(V7)

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Figure 104 Principle of 6to4 tunneling and 6to4 relay
• ISATAP tunneling—An ISATAP tunnel is a point-to-multipoint automatic tunnel. It provides a solution
to connect an IPv6 host to an IPv6 network over an IPv4 network.
The destination addresses of IPv6 packets are all ISATAP addresses. The ISATAP address format is
prefix:0:5EFE:abcd:efgh. The 64-bit prefix is a valid IPv6 unicast address prefix. The
abcd:efgh/64 segments represent a 32-bit IPv4 address, which identifies the tunnel destination
but does not require global uniqueness.
ISATAP tunnels are mainly used for communication between IPv6 routers or between an IPv6 host
and an IPv6 router over an IPv4 network.
Figure 105 Principle of ISATAP tunneling
IPv4 over IPv4 tunneling
IPv4 over IPv4 tunneling (RFC 1853) enables isolated IPv4 networks to communicate. For example, an
IPv4 over IPv4 tunnel can connect isolated private IPv4 networks over a public IPv4 network.
Figure 106 IPv4 over IPv4 tunnel