| VOD (Video on Demand) services have been gaining increasing popularity in recent years. On one hand, the growing user population may lead to the imbalance of the video servers. Some heavily loaded servers may result in longer user perceived latency or even unavailable services. Therefore besides higher performance hardware, load balancing algorithms can be also used to provide better user experience. This paper presents a disk I/O based load balancing algorithm in centralized architecture and gets satisfying simulation results. On the other hand, focused on the VOD services in IPTV, after making a detailed survey on existing matured simulation systems, we implemented our own one according to the specific network topology of Shanghai Telecom. The system architecture is the hybrid of P2P and CDN, and it owns millions of users. We applied the user behavior model learned from the actual user data to our simulations and found that in the hybrid mode the server load is reduced to 30% around compared with the traditional pure CDN mode under ideal network links. In addition, we analyzed the outputs of the simulations under different system parameters and user behavior parameters. Based on our analysis, we provided guidance in some aspects such as user cache settings to Shanghai Telecom which is of realistic significance. |
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