Research And Implementation Of Mpls-based Qos Mechanisms

Traditional IP network with the TCP/IP protocols, which base on datagram and are oriented-connectionless, is designed for efficient data transmission. It provides the type of Best-Effort service, so couldn't guarantee the QoS. With the increasing of real-time service and multi-media application in network, the requirement of QoS became stricter. The present QoS mechanism can't meet the need. So it's necessary to study the QoS mechanism. Based on MPLS technology, this thesis made a deep research on the related techniques which can solve the QoS problems.Firstly, this thesis analyzed several major QoS mechanisms, including main principle and related techniques of MPLS, characteristics of Best-Effort, IntServ and DiffServ model, and comparison of their merits and demerits. The paper also investigated the solution of implementation of IntServ or DiffServ model in MPLS network. The DiffServ-aware traffic engineering combines the MPLS TE with DiffServ model, so is of good scalability and explicit route ability. There is nothing as good as DS-TE to work out the QoS problems of backbone network.Secondly, this paper mainly studied the preemption mechanism in DS-TE model. According to defect of V-PREPT algorithm, the paper proposed two V-PREPT improved algorithms: Bandwidth Optimization and ImprvN-V-PRETP algorithm. The bandwidth optimization algorithm puts avoiding waste of bandwidth in the first place, uses hierarchical approximation method, which enhances restriction of bandwidth preemption, so optimizes the performance in the bandwidth preempted field. The ImprvN-V-PREPT algorithm enumerates all LSPs combination, and picks up the LSPs combination with the least cost. In order to ensure the network's stability, the maximum LSP preempted is set before preemption. By MATLAB simulation, these algorithms are proved that they both have better properties than V-PREPT.Then this thesis simulated the MPLS TE and MPLS DiffServ with OPNET Modeler. It also put forward an experimental solution for realization of MPLS DiffServ in MPLS VPN network. The simulation result showed that MPLS TE has a good ability to optimize the distribution of bandwidth resource and MPLS DiffServ can satisfy traffics with high priority efficiently and improve the network's QoS.Lastly, the paper summarized its study work and proposed a prospect of the nextwork.