Network caching strategies for reservation-based multimedia services on high-speed networks

Abstract

In this paper, we address the problem of minimizing the cost of transferring a multimedia document or a file requested by a set of users geographically separated on a network of nodes. Following the information caching paradigm introduced in the literature for video-on-reservation scheme, we present polynomial-time optimal caching strategies that minimize the total monetary cost of all the service requests by the users on a high speed network of arbitrary topology. We consider a scenario in which a large pool of customers from one or more remote sites on a network demand a document, situated at some site, for their use. We also assume that the users can request the document at different time instants. This process of distributing the requested document incurs communication costs due to the use of communication resources and caching costs of the document at some server sites before it is delivered to the users at their desired time instances. We assume that the size of the document is very small and incurs no communication delays while transferring from one node to another. We consider a generalized version of the problem considering an arbitrary network topology where personalized service agents, manage and control the distribution of the requested document among the users. For a high speed network, we show that a single copy of the requested document is sufficient to serve all the user requests in an optimal manner. As an extension we present a discussion on the case when there are multiple requests at the same instant in time. Using the strategies proposed, the network service providers can decide when, where, and for how long the requested documents must be cached at vantage sites to obtain an optimal solution. Illustrative examples are provided to ease the understanding. © 2002 Elsevier Science B.V. All rights reserved.