NETWORKING REQUIREMENTS FOR INTERACTIVE VIDEO ON DEMAND

A significant driver for the consumer use of high bandwidth in the nea r future will be interactive video on demand (IVOD), A range of servic e types can be deployed, based on a differing sophistication, which mu st be traded against the network costs (bandwidth) and component costs (switch complexity and memory). The potential aggregate bandwidth requ ired is huge (O(1Pb/s)), and thus it is essential to properly engineer the network to reduce the bandwidth required, This paper describes a variety of IVOD scenarios, and introduces a cost function that capture s the combined handwidth and storage requirements of the network, This cost function is used to compare different network engineering altern atives, particularly program caching and stream sharing, The effects o f nonlinear pricing and differing weights of bandwidth and storage are also reflected by the cost function. This cost function can be used b y network designers to determine optimal topology, sharing, and cachin g strategies for desired bandwidth versus memory costs in a particular network deployment, In addition, a simulation model is used to evalua te caching of programs or windows within programs, We show that there are some results that are widely applicable, In particular, the level in the network at which caching should take place is at approximately 80% depth in the distribution tree, above the head end switch in the n etwork hierarchy. We also observe that the bandwidth savings in sharin g streams (actually buffered windows of program content) is fairly sma ll for user behavior based on Zipfs law, The overall intent of this wo rk is to evaluate the effects of various server, cache, and sharing st rategies on the bandwidth and storage requirements of the network and their proper placement within the network.