Fast reroute with pre-established bypass tunnel in MPLS

Abstract

Internet IP networks utilize multiple-protocol label switching (MPLS), which provides a reliable label switched path (LSP). LSP in MPLS domains needs one label at each Ingress label switching router (LSR) to forward the packet. This study presents a novel method to facilitate restoration of LSP in the MPLS network. The proposed method attempts to establish all possible bypass tunnels based on the available bandwidth between two LSRs around the protected label switched router. The Max-Flow Min-Cut theorem is adopted to find the necessary links through which all paths between LSR i and LSR j must pass. All LSPs affected by a LSR failure or a link failure can specify a bypass tunnel that fits its QoS constraints to reroute if there is one. This study also compares the pre-established bypass tunnel (PBT) algorithm and the PBT algorithm with disjoint bypass tunnels (PBT-D). The simulation results indicate that the proposed method has less packet losses in rerouting and can allow more affected LSPs to reroute traffic than RSVP and efficient Pre-Qualify. Additionally, the PBT performs better than PBT-D in terms of correctly receiving ratio and successfully rerouting ratio although PBT-D has the advantages of establishing less paths and fast search time.