Chinese Journal of Computers   Full Text
Title	Hybrid Content Distribution Network and Its Performance Modeling
Authors	JIANG Hai1),2) LI Jun1) LI Zhong-Cheng1)
Address	1)(Institute of Computing Technology, Chinese Academy of Sciences, Beijing 100190) 2)(Graduate University of Chinese Academy of Sciences, Beijing 100039)
Year	2009
Issue	No.3(473—482)
Abstract &   Background	Abstract CDN (Content Delivery Network) and P2P (Peer-to-Peer) are two dominant technologies for large-scale content distribution. CDN may reduce the end-user perceived latency, and P2P can decrease the deployment cost. In this paper, HCDN (Hybrid Content Distribution Network) is proposed to combine complementary advantages of CDN and P2P. In which, user node can retrieve content from both backbone CDN system and P2P autonomy. The network model and distribution operations are presented in detail, including content routing and replica placement. Also the performance evaluation based on fluid model is deseribed, and some metrics such as the evolution of nodes, average downloading time, and service capacity are analyzed. The clear performance benefits of the approach are shown with comparison of conventional CDN and P2P. As shown in the experimental results, HCDN has many advantages on decreasing overload of server, increasing downloading speed and reducing network transmission cost. Keywords hybrid content delivery network; CDN system; Peer-to-Peer; fluid model; performance modeling Background This work was partly supported by the National Key Technology Research Development Program of China under grant No.2006BAH02A11 and the Major State Basic Research Development Program of China under grant No.2007CB310702. The projects focus on the integrated network distribution platform for large-scale audio and video media. The platform includes some subsystems, such as mass media management, efficient network distribution, content copyright protection and user end system. This work will contribute to improve the network distribution efficiency with the proposed HCDN (hybrid content distribution network). In recent years, large-scale content distribution has been an intensively studied research topic. It need meet the requirement of high speed, low latency, and high scalability. CDN (Content Delivery Network) and P2P (Peer-to-Peer) have been widely used in this area. However, CDN and P2P have complementary advantages and weaknesses. The integration of CDN and P2P is still at the preliminary stage, and there are only a few research work concentrated on it. In some related works, P2P architecture is only used in CDN network to support that the surrogates can directly exchange content. In the new approach, content distribution is divided into two stages. In the CDN-level core network, the content is strategically placed from central server to a set of edge servers, and edge servers can exchange content between each other to enhance efficiency. In the P2P-level logical access network, the content is distributed from edge server to user nodes, and the user nodes can concurrently download from both the edge server and other peer user nodes. The performance model based on fluid model is also presented, and the HCDN is evaluated by comparing with conventional CDN and P2P. The experimental result shows the clear performance benefits of the new approach.1)(Institute of Computing Technology, Chinese Academy of Sciences, Beijing 100190) 2)(Graduate University of Chinese Academy of Sciences, Beijing 100039)