Evaluation of content-access QoS for various dissemination strategies in peer to peer networks

Peer to peer (P2P) Network is a high level logical network architecture build over end-user nodes interconnected by a physical network infrastructure. The main interest of their distributed structure is to avoid any centralized point. However, this structure makes difficult the evaluation of the global properties of the network. In the present effort, we propose a method to evaluate quality of service (QoS) for the content access in P2P networks. This method, based on bandwidth distribution evaluation, allows determining statistical content-access QoS guarantees in function of both the level of content replication in the network and the strategies of file dissemination. An implementation of this model, based on real bandwidth measurements on the Gnutella network, is proposed. Three dissemination strategies are evaluated: simple file replication, block file replication, and erasure-encoded (often called forward error correction (FEC) code) block replication. The results shows that statistical QoS guarantees can be provided by controlling the various dissemination parameters, and illustrates the interest of the FEC-based strategy. A simple application in the context of media streaming is finally proposed.