MPLS TE (MPLS Traffic Engineering)

As previously discussed in the book, the maximum number of labels supported in the label stack of the backup path is 3. In situations where more than three labels are needed, a traffic-engineering tunnel is initiated, requiring the following configuration on all routers in the topology to source the tunnel from the loopback IP address of the router.

Enabling MPLS TE on all routers of the topology

The following configuration is required to enable MPLS TE for the IS-IS link state routing protocol on the routers. This allows a router to create TI-LFA backup paths using MPLS TE tunnels.

Let’s apply the following configuration on all the routers to enable MPLS TE on them:

ipv4 unnumbered mpls traffic-eng Loopback0
mpls traffic-eng
router isis IGP
  address-family ipv4 unicast
  mpls traffic-eng router-id Loopback0
!

In summary, this configuration snippet accomplishes the following:

• It enables MPLS TE tunnel...