Ccna routing and Switching Complete Study Guide

Configuring GRE Tunnels

Before you attempt to configure a GRE tunnel, you need to create an implementation plan. 

Here’s a checklist for what you need to configure and implement a GRE:

1.

  Use IP addressing.

2.

  Create the logical tunnel interfaces.

3.

  Specify that you’re using GRE tunnel mode under the tunnel interface (this is optional 

since this is the default tunnel mode).

4.

  Specify the tunnel source and destination IP addresses.

5.

  Configure an IP address for the tunnel interface.

Let’s take a look at how to bring up a simple GRE tunnel. Figure 21.24 shows the 

network with two routers.

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Chapter 21 

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  Wide Area Networks

f i g u r e   21. 2 4     Example of GRE configuration

Internet

GRE tunnel

192.168.10.1/24

Tunnel 0

S0/0/0

63.1.1.2/30

S0/0

63.1.1.1/30