Analysis of the Performance of CacheReplacement Policies for aVideo-on-Demand System
With the wide spread of broadband Internet access, multimedia services are becoming immensely convenient to access and are making a significant contribution to the amount of today's Internet traffic. Comparing with conventional web content access, media--streaming services require significantly more bandwidth because of the huge size of media contents. As a consequence, the limited server capacity and network bandwidths have been proved to be the main bottleneck in the development of video streaming over the Internet. A commonly used method to alleviate traffic congestion in backbone network is setting local cache servers between clients and backbone network, at the edge of local networks. To investigate the effectiveness of local caching on media streaming services, in this thesis five widely used cache replacement policies are simulated based on the request data of a Video--on--Demand (VoD) system and their caching hit rate performance is compared. The cache hit rate results indicate that local caching strategy with appropriate cache replacement policy can achieve fairly high cache hit rate, and therefore, can reduce the network bandwidth and the original server load significantly. Besides, different request pattern and video popularity among different video categories have great impact on the caching results.
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