This document specifies Multiprotocol Label Switching (MPLS) Traffic Engineering Soft Preemption@ a suite of protocol modifications extending the concept of preemption with the goal of reducing or eliminating traffic disruption of preempted Traffic Engineering Label Switched Paths (TE LSPs). Initially@ MPLS RSVP-TE was defined with support for only immediate TE LSP displacement upon preemption. The utilization of a reroute request notification helps more gracefully mitigate the reroute process of preempted TE LSP. For the brief period soft preemption is activated@ reservations (though not necessarily traffic levels) are in effect under-provisioned until the TE LSP(s) can be rerouted. For this reason@ the feature is primarily@ but not exclusively@ interesting in MPLS-enabled IP networks with Differentiated Services and Traffic Engineering capabilities.