Cache location for distributed media service
Yilan Kuai · 2001
Continuous media delivery services such as video have grown significantly in recent years and continue to consume more and more bandwidth of the Internet. To achieve efficient network utilization, multicasting has been employed to share the bandwidth among a group of clients who request the same media stream, as opposed to having a separate unicast connection for each client from the server. Though multicast based media streaming can achieve efficient network utilization, it either increases the service latency (e.g., batching) or it requires the clients to cooperate with the media server (e.g., chaining and patching). To overcome these problems, Cache Multicast Protocol (CMP) was proposed, wherein media stream can be cached at intermediate routers along the path. This thesis proposes algorithms for cache location problem in intermediate router caching scheme and studies their performance. The first protocol, called Static Cache Location Protocol (CLP) that finds a set of k best locations (routers) for caching the media stream for a given set of clients, in such a way that bandwidth sharing is maximized, and service latency and server load are minimized. To achieve this goal, CLP associates a "weight" to each router along the path, which depends on the number of clients supported by that router and distance between clients and that router. Two weight functions have been proposed and their performance is evaluated through simulation studies for various network parameters. Our studies show that small number of caches is sufficient to achieve good service latency. Since the client group is mostly dynamic, the cache locations should be changed dynamically to improve the performance. To this effect, we propose anther algorithm, called Dynamic CLP. The studies show that Dynamic CLP's service latency is comparable to that of CMP using only 40% cache space of CMP. The future work includes adjusting the cache size along with cache replacement policy in CLP.