Configuring Tunneling; Overview; Ipv6 Over Ipv4 Tunneling - HP 10500 Series Configuration Manual

Configuring tunneling

Overview

Tunneling is an encapsulation technology. One network protocol encapsulates packets of another
network protocol and transfers them over a virtual point-to-point connection. The virtual connection is
called a tunnel. Packets are encapsulated at the tunnel source end and de-encapsulated at the tunnel
destination end. Tunneling refers to the whole process from data encapsulation to data transfer to data
de-encapsulation.
Tunneling provides the following features:
• Transition techniques, such as IPv6 over IPv4 tunneling, to interconnect IPv4 and IPv6 networks.
VPN such as IPv4 over IPv4 tunneling, IPv4/IPv6 over IPv6 tunneling, GRE, DVPN, and IPsec.
•
• Traffic engineering, such as MPLS TE, to prevent network congestion.
Unless otherwise specified, the term "tunnel" in this document refers to IPv6 over IPv4, IPv4 over IPv4,
IPv4 over IPv6, and IPv6 over IPv6 tunnels.

IPv6 over IPv4 tunneling

IPv6 over IPv4 tunneling adds an IPv4 header to IPv6 packets so that IPv6 packets can pass an IPv4
network through a tunnel to realize interworking between isolated IPv6 networks, as shown in
The devices at the ends of an IPv6 over IPv4 tunnel must support the IPv4/IPv6 dual stack.
Figure 66 IPv6 over IPv4 tunnel
The IPv6 over IPv4 tunnel processes packets as follows:
A host in the IPv6 network sends an IPv6 packet to Device A at the tunnel source.
1.
After determining according to the routing table that the packet needs to be forwarded through the
2.
tunnel, Device A encapsulates the IPv6 packet with an IPv4 header and forwards it through the
physical interface of the tunnel. In the IPv4 header, the source IPv4 address is the IPv4 address of
the tunnel source, and the destination IPv4 address is the IPv4 address of the tunnel destination.
Upon receiving the packet, Device B de-encapsulates the packet.
3.
If the destination address of the IPv6 packet is itself, Device B forwards it to the upper-layer
4.
protocol for processing. If not, Device B forwards it according to the routing table.
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Figure 66.