A PCE-based redundancy-aware path selection scheme for multi-layer network

With ever increasing requirements posed by significant advances in networking, service providers may use traffic engineering (TE) techniques to efficiently manage resources and provide consistent quality of service (QoS). Briefly, constraint-based path computation involves the pruning of links that do not satisfy constraints and subsequently using the shortest path algorithm on the resulting sub-graph. This process is simple and efficient when the path involves only one domain, but can potentially become severely resource heavy, complex, and inefficient when multiple domains are involved. To address this problem, the Path Computation Element (PCE) architecture has been proposed to allow multi-layer path computation to be simple and efficient. The PCE architecture introduces a special computational entity that will cooperate with similar entities to compute the best possible path through multiple layers. This paper analyses the PCE architecture and the traditional method to computing the routing through multiple layers, and then an improved scheme of path selection for multi-layer network based on PCE and VNTM is present and evaluated on the simulation platform of NSFNET, which is used to avoid traffic redundancy caused by low layer´s invisibility to the high layer.