Research On Traffic Control Strategies For Carrier Network Based On SDN

In order to ensure the transmission quality of user traffic during peak hours,carriers usually purchase high-end routing gear and use over-configured bandwidth,which results in a large number of network resources being idle during off-peak hours.How to improve the network utilization has naturally become the focus of carriers.The emergence of Software Defined Networking(SDN)technology provides a new idea for traffic engineering.Google's B4 network is a successful application of SDN in traffic engineering.For carriers,there's a lot they can learn from Google's B4 solution to improve their network utilization.But the carrier network does not have the features of B4,which are the key factors for the success of the B4 solution,such as simple network structure,single type of network devices and the ability to clearly classify traffic levels.Therefore,how to provide a distributed traffic control strategy based on SDN technology,which can adapt to multi-domain network management scenario,has become the main content of this thesis.This thesis takes the multi-domain carrier network as the research object,and takes the suitable distributed traffic control strategy design as the research goal.The main contributions of this thesis are summarized as follows.Firstly,the traffic control model of the multi-domain carrier network in this thesis is established innovatively by rebuilding the VNE(Virtual Network Embedding)problem in reverse angle.This new issue can be ed into a problem that calculates user access bandwidth(user request in VNE problem)under the constraints of detected remaining bandwidth,total inflow and outflow limits of each domain,optimization objectives,and determined topologies from sources to destinations.From the perspective of network carriers,this issue studies how to improve network utilization by properly scheduling non-real-time background traffic without affecting existing user traffic in a multi-domain management network scenario.Secondly,a distributed traffic control strategy is designed for the dual-domain management scenario of the carrier network.The strategy is based on the prime decomposition method of optimization decomposition theory and is suitable for hierarchical network control architecture based on SDN.The simulation results show that the distributed strategy can improve the average link utilization of the network by about 40%,and it is better than the centralized strategy in convergence time.The design of distributed traffic control strategy based on optimization decomposition theory in the dual-domain scenario provides a research idea and practice for extending to multi-domain scenario.Thirdly,this thesis studies the design of distributed traffic control strategy in the multi-domain management scenario of carrier network.In the multi-domain scenario,the dual decomposition method is used to analyze the decomposability of the Network Utility Maximization(NUM)problem.Because of the complexity of the mathematical scheme,the ring topology is firstly chosen to study,and then the multi-domain management under the random network topology is further studied and the distributed traffic control strategy is designed.The simulation results show that the proposed distributed traffic control strategy can not only significantly improves the average link utilization of network,but also flexibly adapt to the carrier network with different number of domains and the domain scale.Besides,it is superior to the centralized strategy in time performance and improves the scalability of the network to some extent.The distributed traffic control strategies proposed in this thesis are feasible schemes for carriers to carry out traffic engineering based on SDN,and they can effectively solve the problem of low resource utilization and reduce the construction and operation costs of networks.It provides the research basis and solution idea for the future traffic control problem in carriers' multi-domain management network scenario.