Study Of Resource Efficient Multicast Transmission In Software-Defined Networks

After decades of brilliant success,the Internet has encountered its development bottleneck.With more and more protocols and applications adding into the network,network devices have become heavyweight computer systems with complex and high-ly coupled hardware and software.To make things worse,the device architectures are closed due to intellectual property protection.All these facts make network innova-tion a daunting work.Software-Defined Networking(SDN)is an innovative network architecture that aims to remove the barriers of network development.The nature of SDN is decoupling the control plane and the data plane,and making the control plane globally centralized.This architecture greatly simplifies the realization of network con-trol,network device development and network application programming.With SDN,new applications and protocols can be deployed rapidly without the involvement of e-quipment manufacturers.Moreover,many problems that have plagued the Internet for decades have feasible solutions with SDN.For these reasons,SDN has been considered to be the most promising network architecture in the future.Network layer multicast is a highly efficient point to multipoint transmission mode.Receiving path diversity is a unique problem of multicast transmission,which refers to the fact that different receiving paths in a multicast tree may support different data rates.So far,all solutions to this problem,no matter in the traditional networks or in Software-Defined Networks,require to build multiple trees for a single multicast session.Multi-tree multicast not only increases the computational complexity of multicast routing,but also greatly expands the amount of states that should be recorded in the network,which is especially unacceptable in Software Defined Networks(SDNs)as switches usually have very limited flow table spaces.This dissertation studies resource-efficient solutions to receiving path diversity in network layer multicast in SDNs,here resources refer to CPU time,network bandwidth and flow table space.For both lossy data transmission and lossless data transmission,we propose highly efficient single-tree multicast solutions that not only improve multicast transmission rate,satisfy bandwidth allocation fairness,but also minimize the number of flow entries and computational complexity.The main contributions and innovations are summarized as follows.1.For layered coding video applications that allow lossy transmission,draw lessons from the idea of multi-rate multicast,we designed and realized a complete solu-tion for SDNs,which both provides the differentiated services for recipients and scarcely increases the utilization of flow table space in switches.2.For the problem of dynamic update of multicast tree caused by the dynamic change of multicast groups,we study the network bandwidth allocation problem between multicast applications,which is real time and incremental.A mathematical de-scription of the problem is presented and a highly efficient heuristic algorithm is given.The heuristic algorithm achieves the best performance in terms of band-width allocation fairness,routing update cost and computational complexity.3.For lossless multicast transmission in typical campus networks,the problem of receiving path diversity is solved by constructing auxiliary paths for bottleneck links on multicast tree,and the utilization of flow table space is not significantly increased.Targeting at practical applications,all solutions proposed in this dissertation not only achieve the goal of transmission rate improving and bandwidth allocation fairness,but also try to minimize the use of flow table spaces and computational complexity.Therefore,all solutions have practical value.