Offloading VoD Server Organized Dynamically Distributed Cache Using P2P Delivery

A characteristic of video-on-demand (VoD) service is the concentration of access to a few popular content files within short time intervals. Focusing on this characteristic, this paper proposes the concept of a chunk group to reduce the load of both storage and networks on the VoD server. The fundamental idea of this method is to dynamically form a group for clients demanding the same content file and off-load the VoD server load to the groups of clients. The VoD server delivers content to only one client in a group of clients, and the clients deliver the content among the group using peer-to-peer (P2P) communication. This method manages the distributed cache of the fragment of a content file with the cooperating VoD server and clients to reduce the server load. Also, the method provides a failure recovery mechanism so that, even when a client in the group leaves the delivery network, other clients of the group continue the playback. A performance evaluation based on a simulation is carried out to predict the effectiveness of the method. The results show that, with a 12 MB cache capacity on a client side, the number of delivery clients can be improved by 50% at an average arrival interval of 3 seconds and by 11% at an average arrival interval of 9 seconds.