Cast: P2P Patching Scheme for VoD ¢

Providing video on demand (VoD) service over the Internet in a scalable way is a challenging problem. In this paper, we propose ¥§ ¦ Cast- an architecture that uses a peer-to-peer approach to cooperatively stream video using patching techniques, while only relying on unicast connections among peers. We address the following two key technical issues in ¥§ ¦ Cast: (1) constructing an application overlay appropriate for streaming; and (2) providing continuous stream playback (without glitches) in the face of disruption from an early departing client. Our simulation experiments show that¥§ ¦ Cast can serve many more clients than traditional client-server unicast service, and that it generally out-performs multicast-based patching if clients can cache more than¨�©� � of a stream’s initial portion. We handle disruptions by delaying the start of playback and applying the shifted forwarding technique. A threshold on the length of time during which arriving clients are served in a single session in¥� ¦ Cast serves as a knob to adjust the balance between the scalability and the clients ’ viewing quality in¥� ¦ Cast. I