MPLS Traffic Engineering Soft preemption
Global Crossing
Global Crossing
This draft documents MPLS TE Soft Preemption, a suite of protocol modifications extending the current concept of preemption with the goal of reducing/eliminating traffic disruption of preempted TE LSPs. Under present RSVP-TE signaling methods, LSPs are immediately displaced upon preemption. The introduction of a new preemption pending flag helps more gracefully mitigate the re-route process of displaced LSPs. For the brief period soft preemption is activated, reservations (though not necessarily traffic levels) are in effect overbooked until the LSP can be re-routed. For this reason, the feature is primarily interesting in packet oriented MPLS networks with Diffserv and TE capabilities.