Cisco Tunneling

The tunnel interface is a virtual point-to-point link tied to a physical source interface. That is to say, there is a virtual interface that corresponds to a logical interface, and between two interfaces of this type, traffic is wrapped and delivered across a public/private internetwork as if it were a point-to-point link. The tunnel interface has three components:

  • The passenger protocol—The network protocol you are sending over the tunnel, such as AppleTalk, IP, and so on.

  • The carrier protocol—The protocol that encapsulates the data. Generic Route Encapsulation (GRE) is the most commonly used protocol and is needed if multiple protocols are being handled. Cisco also supports Cayman (for AppleTalk over IP), EON (for CLNP over ...

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