Case Studies

This section discusses some of the most commonly used GRE implementations. We will look at some of the GRE features we have already discussed and see how they can be implemented using Cisco IOS Software. PIX does not support GRE, but it can be set up to allow GRE traffic to pass through it.

A Simple GRE Tunnel Connecting Two Private Networks

The most basic GRE implementation you can do is a GRE tunnel between two peer routers, GRE-1 and GRE-2. In this case study, the two routers are connected through a serial link, and then a GRE tunnel is built on top of that link. In order to push traffic into the GRE tunnel, rather than having it go without encapsulation over the plain serial link, a static route statement is added on both the ...

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