Research On SDN Based Long Video Distribution Technology

In recent years,due to the rapid development of network and multimedia technologies,long video multimedia applications such as live video and video conferences have become more and more common,and the operation mode of these long video multimedia applications is very similar to the multicast structure in the network,that is,multiple clients access a video source at the same time,and the simultaneous existence of multiple clients may cause different clients to have different needs.In addition,the differences of hardware devices of multiple clients and the instability of the network itself bring new challenges to the development of the above-mentioned long video multimedia applications.Scalable video coding(SVC)technology is a very promising technology,which can encode a video into several video streams,including a base layer video stream and several enhancement layer video streams,and then realize the video transmission requirements of heterogeneous terminals by controlling the number of video transmission layers.However,due to the transparency of the switch in the traditional network to the multimedia video stream,it is difficult to realize the heterogeneous transmission of SVC video stream in the traditional network.Software defined network(SDN)is a promising technology,which not only greatly optimizes the management of network flow,but also significantly improves the utilization of network resources.The emergence of SDN technology provides a new idea for the transmission of SVC video stream in the network.According to the basic requirements of long video distribution,this thesis designs a hierarchical multicast system architecture based on SDN,and proposes two Hierarchical Multicast spanning tree algorithms.Firstly,the branch node spanning tree algorithm and the cut point spanning tree algorithm are proposed,both of which can realize the distribution of layered multicast streams and dynamically adjust the number of layers of video streams.In addition,the branch node spanning tree algorithm can reduce tree consumption and video delay.This algorithm is mainly applied to network nodes and link resources which are relatively precious.For example,if you want to use less switches and network cables to achieve a multicast;the cut point spanning tree algorithm can better optimize the link For the use of bandwidth,this algorithm is mainly applied to the situation where the network bandwidth resources are relatively scarce.For example,when the network situation is not good and there are many terminals using bandwidth resources.Secondly,this thesis introduces the architecture of hierarchical controllable multicast system based on SDN,and then explains each module separately.The video server is mainly used to encode SVC video stream and transmit SVC video stream.The management server mainly collects network information and user information,establishes logical multicast tree according to Hierarchical Multicast spanning tree algorithm,and SDN controller mainly provides forwarding rules to Open Flow switch to realize specific data forwarding.Finally,a comparative simulation experiment is carried out to test the feasibility of the layered multicast system architecture,the performance of the two algorithms and the impact of congestion probability threshold on the packet loss rate of the algorithm.The experimental results show that the video distribution system architecture can achieve the distribution of layered multicast streams,the branch node spanning tree algorithm can improve the tree consumption of the whole network,and the cut node spanning tree algorithm can improve the packet loss rate Link bandwidth utilization of the whole network.With the increase of congestion probability threshold,packet loss rate of branch node spanning tree algorithm and cut point spanning tree algorithm increases gradually.