H3C Technologies H3C S10500 Series Switches - Manual (Page 158)

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Tunneling configuration
NOTE:
You can set an Ethernet port to operate in route mode (Layer 3) or bridge mode (Layer 2) by using the port
link-mode route command (see
Layer 2—LAN Switching Configuration Guide).
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 and de-encapsulated at both ends of a tunnel. 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.
• Virtual Private Networks (VPNs) for guaranteeing communication security, such as IPv4 over IPv4
tunneling, IPv4/IPv6 over IPv6 tunneling, Generic Routing Encapsulation (GRE), Dynamic Virtual
Private Network (DVPN), and IPsec tunneling.
• Traffic engineering, such as Multiprotocol Label Switching traffic engineering (MPLS TE) to prevent
network congestion.
Unless otherwise specified, the term tunnel used throughout this document refers to an IPv6 over IPv4,
IPv4 over IPv4, IPv4 over IPv6, or IPv6 over IPv6 tunnel.
IPv6 over IPv4 tunneling
Implementation
IPv6 over IPv4 tunneling adds an IPv4 header to IPv6 data packets so that IPv6 packets can pass an IPv4
network through a tunnel to realize interworking between isolated IPv6 networks, as shown in Figure 65 .
The IPv6 over IPv4 tunnel can be established between two hosts, a host and a device, or two devices. The
tunnel destination node can forward IPv6 packets if it is not the destination of the IPv6 packets.
NOTE:
The devices at both ends of an IPv6 over IPv4 tunnel must support the IPv4/IPv6 dual stack.