Research On Constraints Routing Algorithm Based On MPLS Traffic Engineering

Constraint-based routing algorithm can calculate all possible paths according to constraints which satisfy one or more of the quality of service (QoS), and can choose the one best path according to certain rules. Compared to the traditional shortest path first routing algorithm, constraint-based routing algorithm not only can find a feasible path for business flows which satisfies the QoS, but also can make business flows even and reasonable by any other routing algorithm. Thus, it can largely overcome the bottleneck of shortest path first routing algorithm, reduce the probability of congestion, improve the efficiency of using network resources and achieve the goal of optimizing network performance. So, researching and proposing efficiency constraint-based routing algorithm that based on Multi-Protocol Label Switch traffic engineering which are of great significance for the actual network application. This algorithm can provide the QoS that satisfies business and mostly optimize the capacity of network by making reasonable control of routing.Constraint routing algorithm decides how to choose the route, which is one of the core issue came down to the traffic engineering and the point researched in the paper. This paper analyzes the constraint routing mechanism, mainly compares the traditional Shortest Path First algorithm and the general Constraint Shortest Path First algorithm. Based on the existing CSPF algorithm, this paper puts an improved algorithm based on multi-QoS constrains, and then discusses the design ideas of the algorithm as well as algorithm process and analyzes the time complexity of algorithm. The most important change in improved algorithm is adding the constrain mechanism of delay. It starts from the minimum delay path set, and considers the relocation issues of key links, then chooses the bottleneck as the key link in this set. It hopes to consume less network resources and to make traffic load be distributed on free links as far as possible so as to achieve the goal of optimizing network performance. This paper builds the MPLS network environment by NS-2, and simulates the load-balancing requirements of MPLS traffic engineering. Focusing on NS-2 simulation platform, the paper analyzes and comprises the differences between the improved algorithm and the existing algorithm respectively in tree, ring and other complex network topologies. At last, this paper points out the shortcomings of this algorithm and the further research directions. Through the result of simulation, the Scrable Constraint Shortest Path First algorithm proposed in the paper can improve accepted probability of coming requests, bandwidth resources utilization, the rejection rate in the non-equilibrium load network and the complexity of calculate time, compared to existing scrable CSPF algorithms. S-CSPF algorithm proposed is good to the expansion application of actual network. It is very significance to realize the dynamic traffic engineering based on MPLS network, load balance, avoid the congestion and optimize network utilization.