Research On QoS Routing Based On TeXCP Over MPLS Network

In this paper, we analyzed some load balancing algorithms and QoS routing models in MPLS network. The most important one is TeXCP (Expcilit Congesstion control Protocol with Traffic Engirneering) presented in Sigcomm 05. TeXCP is a load balancing algorithm for best-effort traffics in MPLS network, and has stability of control theory. But no consideration of QoS issues is given in the paper.Based on above analysis,we propose a TeXCP based QoS routing algorithm, QoSTX, which allow bandwidth guaranteed traffics(QoS traffic) and best-effort traffic to share bandwidth dynamically. The basic starting point is that best-effort traffic can be automatically adjusted to reach multipath load equilibrium by using TeXCP; the bandwidth requirement of QoS traffic can be guaranteed by admission control and resource reservation. When two classes of traffics compete link bandwidth, the requirement for resources is first guaranteed, at the same time, the fractions of best-effort traffics on their path are dynamically adjusted by using TeXCP to achieve load balance and avoid congestion.The framework of our approach proposed in this paper has three major components. 1. An extension of probing function of TeXCP agent, which includes path reservable bandwith and path utility in reduced network, which is obtained by removing QoS traffics from original network. 2. A modification of TeXCP, so that new algorithm can effectively balance best-effort traffics in the integration network. 3. Addition of admission control, path selecton and resource reservation mechanisms in edge nodes.The algorithm has been implemented in Networks Simulator-2(NS-2) and MNS 2.0 by the author. The simulation results show that the new algorithm intergrates the best-effort traffics and the QoS traffics effectively, and decreases maximum link utilization factor and reduced congestion state of networks. At the same time of guarantee of bandwidth of QoS traffics, throughput of network is increased.