A Comparison of Continuous Media Stream Proxy Caching Policies

F. Liu and D. Makaroff (Canada)


Continuous Media, Proxy Caching, LFU, SCU


As the computing capacity and network bandwidth at clients increase rapidly, the bottleneck for distributing continuous media streams is pushed upstream to the network backbone and the media source server. Compared with traditional text or image files, streaming media files need very large storage space, large bandwidth to be transferred, and a time-constrained service to ensure the play back quality. To reduce server workload and network bandwidth consumed by media streams, continuous media stream proxy was introduced. Different proxy caching policies were also proposed to maximize the utilization of the limited proxy space and the network bandwidth saving. In this paper, using bandwidth saving as a metric, we compare three media proxy caching policies: Smallest Caching Utility (SCU), Least Frequently Used (LFU), and Least Recently Used (LRU). Our comparisons investigate the impact of proxy size, time interval, and various workload characteristics on these three policies. Our simulation results show that time interval is a significant parameter for SCU, and that the policies behave differently under various workload parameters (e.g. shape parameters of a of Zipf-ilike distribution popularity).

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