Research And Design Of Multimedia Transmission Over Pub/Sub System In SDN Networks

As a distributed message middleware,publish-subscribe system realizes the decoupling between sender and receiver of message.SDN network has the characteristics of controllability and programmability.Combining publish-subscribe system with SDN network can give full play to the characteristics of both and realize the functions that traditional network not accomplish.The data transmitted in the Internet of Things includes not only text data,but also multimedia data such as pictures,surveillance videos.The traditional publishing and subscribing system adopts a cascade network architecture,which does not control the underlying routing and communication equipment.Therefore,it is difficult to provide quality assurance for multimedia data transmission.SDN "control-forwarding"separated structure support system programmed network devices at runtime,and SDN-based publishing and subscribing system made multimedia data transmission possible.In order to realize the transmission of multimedia data in SDN publishing and subscribing system,this paper designs the publishing and subscribing system architecture,routing and forwarding,and quality assurance based on SDN.The innovations of this paper include:1)It organizes and manages the devices,switches,hosts,services and applications of the Internet of Things in a clustered and hierarchical way,which facilitates the expansion of the scale of the system.Cluster consists of multiple switches,multiple hosts and a cluster controller.On the cluster controller,the main functions of publish-subscribe system are designed and implemented,and intra-cluster autonomy and inter-cluster interconnection are accomplished.Clusters and clusters are connected dynamically through boundary switches.The function of global administrator is designed to organize all groups in the system(i.e.group administrators)again and complete hierarchical management.2)There are many shared event name trees in the Internet of Things,and there are many subscriptions and publications for each event name.In this paper,a multi-source multicast event routing algorithm is proposed to achieve dynamic load balancing and minimize the forwarding cost.3)A two-tier quality assurance scheme is provided.Users submit QoS requests through a unified publish-subscribe interface.Administrators aggregate all QoS requests and make global analysis and decision-making,and send the decision-making results to each cluster controller.The cluster controller converts it into event forwarding parameters of all switches in the cluster according to the global allocation of QoS parameters.At the same time,the real-time state measurement and analysis are carried out to ensure that high priority events are forwarded according to the requirements of QoS in the local scope.4)The subscription of multiple users on the host will lead to high concurrency.The system sets up WSN layer on the client side and adopts two-level caching event delivery scheme and load balancing strategy to improve the stability of message forwarding.This system realizes all functions of the publish/subscribe system in the real network environment built by SDN switching agency,and provides a perfect transmission quality assurance.After a lot tests,the publish/subscribe system based on SDN runs stably in the physical environment,and supports multimedia transmission and user requirement negotiation.The test results verify the effectiveness of the system's quality assurance scheme.