Ipv4 Over Ipv4 Tunneling - HP 6125G Configuration Manual

notation. For example, 1.1.1.1 can be represented by 0101:0101. The part that follows
2002:abcd:efgh uniquely identifies a host in a 6to4 network. The tunnel destination is
automatically determined by the embedded IPv4 address, which makes it easy to create a 6to4
tunnel.
The tunnel can forward IPv6 packets because the 16-bit subnet number of the 64-bit address prefix
in 6to4 addresses can be customized and the first 48 bits in the address prefix are fixed to a
permanent value and the IPv4 address of the tunnel source or destination.
Figure 59 6to4 tunnel
6to4 network
Site 1
ISATAP tunneling
•
An ISATAP tunnel is a point-to-multipoint automatic tunnel. The destination of a tunnel can
automatically be acquired from the embedded IPv4 address in the destination address of an IPv6
packet.
When an ISATAP tunnel is used, the destination address of an IPv6 packet and the IPv6 address
of a tunnel interface both adopt special ISATAP addresses. The ISATAP address format is
prefix(64bit):0:5EFE:abcd:efgh. The 64-bit prefix is the prefix of a valid IPv6 unicast address, but
abcd:efgh is a 32-bit source IPv4 address in hexadecimal, which might not be globally unique.
Through the embedded IPv4 address, an ISATAP tunnel can be automatically created to transfer
IPv6 packets.
The ISATAP tunnel is mainly used for communication between IPv6 routers or between a host and
an IPv6 router over an IPv4 network.
Figure 60 Principle of ISATAP tunneling

IPv4 over IPv4 tunneling

IPv4 over IPv4 tunneling (specified in RFC 1853) is developed for IP data packet encapsulation so that
data can be transferred from one IPv4 network to another IPv4 network.
6to4 router
IPv4 network
Device A
6to4 tunnel
121
6to4 router
6to4 network
Site 2
Device B