Example 33 Configuring a Basic Mpls Te Tunnel Interface

interface Tunnel0

ip unnumbered Loopback0

tunnel mode mpls traffic-eng tunnel destination destination-ip tunnel mpls traffic-eng path-option 10 dynamic

Table 3-1 describes the key commands in this configuration.

Table 3-1. Commands for Configuring a Basic MPLS TE Tunnel Interface

Command

Description

interface TunnelO

MPLS Traffic Engineering tunnels are represented as tunnel interfaces in the Cisco IOS Software. From this perspective, an MPLS Traffic Engineering tunnel is no different from a GRE tunnel or any other kind of tunnel you can configure.

ip unnumbered LoopbackO

Cisco IOS Software does not forward traffic down an interface without an IP address on it, so you need to assign an IP address to the MPLS Traffic Engineering tunnel you've just created. However, because TE tunnels are unidirectional and don't have the concept of a link neighbor with which to communicate, it's a waste of addresses to put an additional IP address on the interface.

tunnel mode mpls traffic-eng

Tells the Cisco IOS Software that this tunnel interface is an MPLS Traffic Engineering tunnel. Other possible tunnel modes are GRE, DVMRP, and so on.

tunnel destination destination-ip

Tells the Cisco IOS Software what the tunnel's endpoint is. The IP address specified here is the MPLS Traffic Engineering RID (more on that later) of the router to which you want to build a tunnel. The destination-ip in this case is the Loopback0 interface on the tunnel's tailend router.

tunnel mpls traffic-eng path-option 10 dynamic

Tells the Cisco IOS Software how to generate the path from the tunnel headend to the tunnel tail. This command is covered in more detail in Chapter 4.

As you can see, a basic MPLS Traffic Engineering configuration is simple. You need to configure a few more things on your routers before MPLS Traffic Engineering tunnels will actually be set up and used, but not much more. You can tweak plenty of knobs to change how MPLS Traffic Engineering tunnels behave in your network.

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