Acceleration of WWW Service with Distributed Cache Technology
Eiji Kawai · Institutional Repositories DataBase (IRDB) · 2001
Acceleration of WWW Service with Distributed Cache TechnologyGreat varieties of cache technologies are applied to improve the quality of WWW services.A distributed WWW cache system is such a strong solution where cache of a single proxy server is shared by other proxy servers.It can reduce WWW service latency, traÆc on the Internet, load of WWW servers, etc. Internet cache protocol (ICP) is one of the protocols widely employed by the distributed WWW cache systems.Using ICP, the proxies scattered all over the world can easily cooperate with each other and increase their cache hit rate.On the other hand, the traÆc generated by ICP might cause a consumption of network resources because it does not usually convey any WWW object data.Despite this disadvantage, ICP has been employed even in inappropriate situations because there is no quantitative analysis of the ICP traÆc.Obviously, a system analysis based only on the hit rate, which is the most frequently used index for performance of a cache system, is inadequate to evaluate the eect of the distributed WWW cache system.In this dissertation, rstly I give q u a n titative traÆc analyses of distributed WWW cache systems especially focused on local area networks (LANs) and wide area networks (WANs).From a viewpoint of LAN, ICP simply increases the amount of ICP traÆc passing through the boundary router that connects the LAN and the rest of the world.Because the network bandwidth between the LAN and the WAN is highly limited in many cases, ICP can cause a severe performance degradation.From a viewpoint of WAN, ICP can actually decrease the HTTP traÆc on the Internet by retrieving HTTP objects not from distant origin servers but from possibly closer proxy servers.However, the ICP traÆc on the Internet might cancel the traÆc reduction.In my analysis, I gure out the communication model of the system and investigate the in uence of several parameters on the traÆc.The contribution of this dissertation includes that it speci es the proper and improper situation where ICP can be employed.With this analysis, WIDE cache bone, one of the largest distributed WWW cache systems in Japan operated by WIDE project, is recon gured at many proxy servers to cease i I wish to express my gratitude to professor Kotaro Minato, my advisor and committee chairman, for his support, advice and encouragement.Without his kind cooperation, I could not complete this dissertation.I w ould also like to thank professor Akira Fukuda for his helpful support on my committee.His useful comments helped me to nish