| Because of the immediately-play video viewing mode,the streaming media based video on demand(VOD)system has attracted more and more Internet users.As a streaming media VOD system based on P2P protocol,the v6Channel breaks the traditional performance limitation of centralized server system,and distributes the video contents through the sharing of the users.As the draft standard of IETF in the field of streaming video service,PPSP protocol will become the standard for the next generation P2P network.Based on PPSP protocol,the objective of this thesis is to study and improve the v6Channel system’s scalability,so that the system can support more users.Firstly,we study the structure design of v6Channel system in the aspect of scalability,and analyze the technological bottlenecks,which limits the scale of the system.Then we set up the test environment in PlanetLab to simulate the VOD behaviors of the users,through which the technical problems limiting the scalability are concluded,for example,the disorganized resource distribution,plenty of redundant interactive information and unreasonable assignment of resources.Secondly,according to the analysis of the system and combined with the guidance of ppsp protocol,we introduce the supernode entity to share the pressure of the server and revise the generation strategy of peerlist to improve the resource assignment of the system.Last,evaluation has been done to compare the improved system with the existing v6Channel in terms of system pressure,original delay for the nodes and the time to get the resources.Testing results show that the improved system has better performance in terms of scalability,which is important for the real deployment of v6Channel system. |
