H3C Technologies H3C SecPath F1000-E - Manual (Page 147)

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Tunneling Configuration
NOTE:
The term router in this document refers to a network routing device running a routing protocol.
This chapter includes these sections:
• Tunneling Overview
• Tunneling Configuration Task List
• Displaying and Maintaining Tunneling Configuration
• Troubleshooting Tunneling Configuration
Tunneling Overview
Introduction to the Tunneling Technology
Tunneling is an encapsulation technology, which utilizes one network protocol to encapsulate packets of
another network protocol and transfer them over the network. A tunnel is a virtual point-to-point
connection providing a channel to transfer encapsulated packets. 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:
• Transition techniques, such as IPv6 over IPv4 tunneling, to interconnect IPv4 and IPv6 networks.
• Virtual private networks (VPNs) for guaranteeing communication security, such as generic routing
encapsulation (GRE), and IPsec tunneling.
• Traffic engineering, such as multiprotocol label switching traffic engineering (MPLS TE), thus
preventing network congestion.
The preceding tunneling technologies require that you create virtual Layer 3 interfaces (tunnel interfaces)
at both ends of a tunnel, so that devices at both ends can send, identify, and process packets transferred
through the tunnel.
NOTE:
•
The term tunnel used throughout this document refers to an IPv4/IPv6 transition tunnel, IPv4 over IPv4
tunnel or IPv6 over IPv6 tunnel unless otherwise specified.
• For information about GRE, see GRE Configuration in the VPN Volume.
• For information about IPsec, see IPsec Configuration in the Security Volume.
Introduction to IPv4/IPv6 Tunnels
The expansion of the Internet results in scarce IPv4 addresses. The technologies such as temporary IPv4
address allocation and Network Address Translation (NAT) relieve the problem of IPv4 address shortage
to some extent. However, these technologies not only increase the overhead in address resolution and