OAZE: A network-friendly distributed zapping system for peer-to-peer IPTV

IPTV systems attracting millions of users are now commonly deployed on peerto-peer (P2P) infrastructures. Each channel is associated with a P2P overlay network formed by the users who receive, watch and redistribute this channel. However, zapping from one P2P overlay to another requires a significant amount of time, and therefore the P2P IPTV experience is not as good as for a multicastbased IPTV. In order to speed up the switching process and to reduce the overall cross-domain traffic generated by the IPTV system, we propose a distributed algorithm called OAZE for Overlay Augmentation for Zapping Experience. The main idea is that every peer maintains connections to other peers in a subset of all channels to which it is likely to zap, and collaborates with the other peers in its channel for the remaining channels. We present in this paper the OAZE mechanism. We focus in particular on the channel assignment problem, which consists in determining the optimal distribution of the responsibility to maintain contact peers in other channels in a given overlay. We propose an approximate algorithm having guaranteed performances in comparison to the optimal one, and an algorithm that is simpler and more practical. Simulations show that OAZE leads to substantial improvements on the connections between peers, resulting in less switching delay and lower network cost. This approach is ∗Corresponding author Supported by project P2Pimages, of the French Media & Networks cluster Preprint submitted to Elsevier August 12, 2011 overlay independent and is an appealing add-on for existing P2P IPTV systems.