1-11 Tunneling ConfigurationWhen configuring tunneling, go to these sections for information you are interested in:z Tunneling Overviewz Tunneling Configuration Task Listz Configuring an IPv6 Manual Tunnelz Configuring a 6to4 Tunnelz Configuring an ISATAP Tunnelz Configuring an IPv4 over IPv4 Tunnelz Configuring an IPv4 over IPv6 Tunnelz Configuring an IPv6 over IPv6 Tunnelz Configuring a GRE over IPv4 Tunnelz Configuring a GRE over IPv6 Tunnelz Displaying and Maintaining Tunneling Configurationz Troubleshooting Tunneling ConfigurationTunneling OverviewIntroduction to the Tunneling TechnologyTunneling is an encapsulation technology, which utilizes one network protocol to encapsulate packets ofanother network protocol and transfer them over the network. A tunnel is a virtual point-to-pointconnection providing a channel to transfer encapsulated packets. Packets are encapsulated anddecapsulated at both ends of a tunnel. Tunneling refers to the whole process from data encapsulation todata transfer to data decapsulation.Tunneling provides the following:z Transition techniques, such as IPv6 over IPv4 tunneling, to interconnect IPv4 and IPv6 networks.z Virtual private networks (VPNs) for guaranteeing communication security, such as generic routingencapsulation (GRE) and dynamic virtual private network (DVPN).z Traffic engineering, such as multiprotocol label switching traffic engineering (MPLS TE), thuspreventing network congestion.The preceding tunneling technologies require that you create virtual Layer 3 interfaces (tunnelinterfaces) at both ends of a tunnel, so that devices at both ends can send, identify, and process packetstransferred through the tunnel.
