How Does MPLS-TE Interact with QoS
MPLS Traffic Engineer is sometimes promoted as a QoS solution (it seems bandwidth calendaring is a permanent obsession of some networking engineers, and OpenFlow is no more a solution than MPLS-TE was ;), but in reality it’s pretty hard to make the two work together seamlessly (just ask anyone who had to implement auto-bandwidth MPLS-TE in a large network).
Not surprisingly, we addressed the topic during our MPLS Tech Talk (now part of MPLS Essentials webinar).
DS-TE makes your interface-level QoS configuration and LSP configuration congruent. The IGP will advertise specific amounts of bandwidth as configured in the QoS configuration for each hop along the network. So if your lower path is configured for 0% BE and 100% EF, the data LSP would never traverse it during a failure. I've rarely seen anyone implement DS-TE in a production network.