An LSP tunnel may need to be rerouted due to conditions based on administrative policy, for example, when a more optimal route becomes available, when a resource fails along the LSP, or when a failed resource is reactivated. The SE reservation style allows a smooth transition from an old LSP to a new LSP with the make-before-break operation. This style also permits the old and new LSPs to share a single reservation over links they have in common, preventing double-counting of resources.