This topic is to discuss the following lesson:
You only created a one way tunnel, meaning since it is unidirectional, the ping should not work. Is the reverse path being chosen via IGP and not using the tunnel ?
Hello Iman
MPLS TE tunnels are indeed unidirectional in nature. If you want to ensure traffic in the other direction is applied with similar TE criteria, then you must create a second TE tunnel for the return traffic.
The path of the return traffic is determined simply by the regular IP routing tables and MPLS forwarding tables that exist within the infrastructure.
In this particular lab, the return traffic does indeed return via the non-TE MPLS and IP routing mechanisms. In the lesson, the verification steps Rene takes are to observe outgoing traffic that uses the tunnel.
I hope this has been helpful!
Laz