MPLS provides native TE capabilities that can improve network efficiency and service guarantees. These MPLS TE capabilities bring explicit routing, constraint-based routing, and bandwidth reservation to MPLS networks. MPLS TE relies on extensions to existing IP protocols (IS-IS, OSPF, and RSVP). MPLS TE also supports its routing and bandwidth-reservation capabilities per class through the DS-TE extensions. DS-TE retains the same overall operation characteristics of MPLS TE but introduces minor protocol extensions to accommodate multiple classes. DS-TE enforces BCs on network links that complement the bandwidth allocation that DiffServ can provide in the forwarding plane provides. DS-TE can use two different BC models (MAM and RDM). Last, MPLS TE provides a fast protection mechanism for link and node failures using FRR. This mechanism relies on presignaled backup TE LSPs to provide fast protection (in milliseconds) in a scalable manner to other TE LSPs.