Ciena Corporation
Methods and Systems preventing Make Before Break failures during soft preemption in MPLS

Abstract:

A method implemented at an intermediate node in a Multiprotocol Label Switching (MPLS) network to prevent Make Before Break (MBB) failures during soft preemption of a lower priority Label Switched Path (LSP) includes, responsive to a determination the lower priority LSP needs preemption, determining a first route of a higher priority LSP which caused the preemption and bandwidth on the first route; determining a second route which is a current route of the lower priority LSP and bandwidth on the second route; analyzing the first route and the second route to determine one or more excluded interfaces which do not support the lower priority LSP due to the higher priority LSP; and transmitting a preemption message designating a soft preemption of the lower priority LSP including all of the excluded interfaces therein towards an ingress node along the second route.