Research On Key Techniques Of Dynamic Multicast Based On SDN

The rapid development of mobile Internet,cloud computing and online media has gradually changed the form and business needs of the Internet,which is reflected in the following four aspects: 1)The topology of the underlying network may be dynamically changed according to the user's resilience needs;2)the number of mobile terminals within the network explosive growth;3)streaming media has become a major contributor to network traffic;4)video-on-demand,online session and other streaming media-related distributed applications become a class of important network services.This new Internet development trend can be summarized as follows: the underlying network and terminal equipment become dynamic,network traffic becomes multimedia,and information producers become multiple.Therefore,there is a need for an efficient means of communication to provide strong support for multi-party-participation distributed applications.Unicast,broadcast and multicast is the three main types of communication within the Internet.Compared with unicast and broadcast,multicast is an ideal means to support such applications.It does not need to establish a point-to-point connection between multi-party participants as unicast,which reduces the consumption of bandwidth resources.Moreover,it does not need to send large amounts of packets to all branches of the network through flooding,which effectively reduces the number of invalid packets within the network and mitigating network conflicts.It can be seen that multicast communication is becoming more and more important in the current trend of new network development.However,the multicast framework that provides a network with multicast group management and a multicast routing algorithm is universal and exclusive,which leads to two shortcomings to multicast communication.First,the multicast framework's default multicast routing algorithm is not specially designed for dynamical networks,which negatively affects the quality of service(Qo S)of multicast trees.Second,customized multicast routing algorithms cannot be deployed over the framework.Therefore,the multicast framework cannot simultaneously satisfy the Qo S requirements of different application scenarios.Moreover,the widely used multicast routing protocols,such as core-based trees(CBTs)or protocol-independent multicast-sparse mode(PIM-SM),establish shared trees based on a rendezvous point(RP).This feature causes multi-source multicast to suffer from hot-spot traffic concentration and optimal RP selection problems.In order to solve this problem,an additional multicast framework must be deployed to the network,and then the multicast routing algorithm for dynamic multicast or other Qo S requirements should be deployed on this additional multicast framework.However,the multicast framework was initially designed to be exclusive and closed,without considering scalability and exibility;when there are two multicast framework in the network,there will be a serious conflict between them..To endow scalability and exibility to multicast communications,the traditional solution is to deploy customized multicast routing algorithms over an application-layer multicast(ALM)framework;however,ALM needs the support of dedicated application-layer programs that may make it incompatible with typical multicast applications.Developers of multicast applications have to develop dedicated multicast group management protocols and corresponding programs for each multicast routing algorithm.This violates the reusable principles of the software industry.Therefore,how to deploy a multicast routing algorithm suitable for dynamic multicast application scenarios while maintaining compatibility with typical multicast applications becomes a problem to be solved.In this thesis,we study the dynamic multicast from four aspects: physical framework,mathematical theory foundation,routing algorithm and practical application.Then,we proposed an SDN-based multicast framework that allows users to deploy custom multicast routing algorithms over the framework without interfering with existing multicast frameworks while maintaining compatibility with typical multicast applications.Moreover,based on this framework,we propose a non-rearrangeable dynamic multicast routing algorithm and a rearrangeable multicast routing algorithm for dynamic application scenarios.Finally,we use the distributed memory to verify the proposed multicast framework and the multicast routing algorithms.The main research contents and innovations of this thesis include:we propose an innovative multicast framework leveraging SDN.The multicast group management of this framework is based on an ingeniousmulticast-address mapping mechanism to take over specified multicast group from existing multicast framework.In this case,this multicast framework and existing multicast framework are isolated from one another at the network layer.Since this isolation does not need the support of dedicated Application-Layer program,the typical multicast application can be seamlessly compatible with this multicast framework.Based on this framework,customized multicast routing algorithms can be deployed to satisfy the requirements of different application scenarios.A packet loss avoidance mechanism based on SDN is proposed for avoiding packet loss caused by perturbation of multicast tree.In order to describe the dynamic multicast and rearrangeable multicast routing algorithm in a more clear,accurate and comprehensive way,we introduce the bandwidth of the link into the time-varying graph theory and extend the theory from the time domain to the two-dimensional space composed of time domain and multicast domain.A new non-reconstructed multicast routing algorithm based on anycasting model is proposed for adapting the high dynamic characteristics of multicast and solving the defects caused by Rendezvous Point.Based on the above four research results,we propose an SDN based distributed shared memory for distributed applications...