Research On Dual Constraints Routing Scheme In MPLS-TE

With the development of network technology, more commercial applications started by the IP network to carry. Voice, video and other multimedia services are applied in the network, which requires a higher network capacity and transmission technology. But the traditional IP network uses the shortest path algorithm to choose path, this method overlooks the available link capacities and the business’s requests, it can’t satisfies the quality of service and can’t uses the network resource rationally. To solve this problem, it’s hard to meet the demand just by adding more infrastructures to extend the capacity of the network. A probably way is to improve the current transmission technology while adding the network resource. So traffic engineering is proposed, its implementation can be directly used to relieve network congestion and to distribute the network resource reasonably. In addition, it can achieve the QoS guarantee. MPLS is regarded as a powerful tool to realize traffic engineering. It makes full use of the advantage of the switch function and traffic management of the second layer and the flexible routing function of the third layer, indirectly. The thesis will deploy around MPLS TE.A new routing algorithm DCRA(Dual Constraints of Routing Algorithm) base on link criticality and link saturation is presented via analyzing MIRA(Minimum Interference Routing Algorithm) and DORA(Dynamic Online Routing Algorithm in depth. This algorithm is composed of off-line preprocessing stage and on-line routing stage. Off-line preprocessing stage according to the topological structure of the network for the node pair to establish DP (Disjointed Path) database, and to identify Link Critical Value by DP database; On-line routing stage, network source will be divided into low load,load and high load three stages according to the network bandwith resource utilization ratio, and then determine the link saturation value according to certain strategy. In low load condition, it chooses the shortest path priority algorithm for route selection, while in load and high load condition, we first obtain the link cost function through adding the link ciritical value and the link saturation according to the weighting factor, then we use the Dijkstra algorithm for the business route. The simulation results show that compared with the DORA algorithm and CSPF algorithm, the new algorithm can significantly improve network throughput and reduce the average path length of real-time traffic. It guarantees QoS of real-time traffic while improving the utilization of network resources.