Path Selection Analysis in MPLS Network Based on QoS

Multi-Protocol Label Switching (MPLS) has been proposed as a new approach for integrating layer 3 routing with the layer 2 switching. It integrates the label swapping paradigm of layer 2 (e.g. ATM and Frame Relay) with the routing of layer 3 (e.g. IP and IPX). In the MPLS networks, constraint-based routing computes routes that are subject to constraints such as bandwidth and administrative policy. Because constraint based routing considers more than network topology in computing routes, it may find a longer but lightly loaded path better than the heavily loaded shortest path. In this paper we propose a new constraint based routing algorithm for MPLS networks. The proposed algorithm which is a modification of Wang-Crowcroft algorithm, uses both bandwidth and delay constraints. It means that the reservable bandwidth of all of the links along computed path must be equal to or greater than the bandwidth constraint value and the delay of the path must be less than or equal to the delay constraint value. In the proposed algorithm, the best path is selected based on proposed algorithm. Simulation results show that in comparison with the other methods, the proposed algorithm has a better performance.