Analysis of Content Distribution Architectures in P2P Systems

This paper takes a novel perspective to P2P networking. Can a P2P system be used for the distribution of files with time-critical data such as relevant software patches or virus footprints updates? We examine and compare different distribution architectures based on linear and tree topologies built on top of the P2P overlay, including in the analysis the presence of heterogeneous bandwidths, both symmetric and asymmetric access links. We propose an analytical solution of the distribution process that not only yields the mean download time but also the distribution of the download times. We validate the analytical model against a Monte Carlo based numerical solution, which can also be used to analyze scenarios where correlation and dynamic behavior make the theoretical analysis too approximate. The insights we gain are used to devise modifications of the distribution strategies that achieve good performance even when slow access links and incomplete knowledge jeopardize the fast delivery of the content. Indeed, with proper (yet simple) mechanisms the average completion times achieved are close to the minimal (lowest possible) ones, which indicates that the P2P paradigm can be used for delivering time-critical data. Finally the presence of non-cooperative peers is analyzed, assessing their impact for different scenarios

PLM: Fast Convergence for Cumulative Layered Multicast Transmission Schemes

A major challenge in the Internet is to deliver live audio/video content with a good quality and to transfer files to large number of heterogeneous receivers. Multicast and cumulative layered transmission are two mechanisms of interest to accomplish this task efficiently. However, protocols using these mechanisms suffer from slow convergence time, lack of inter-protocol fairness or TCP-fairness, and loss induced by the join experiments. In this paper we define and investigate the properties of a new multicast congestion control protocol (called PLM) for audio/video and file transfer applications based on a cumulative layered multicast transmission. A fundamental contribution of this paper is the introduction and evaluation of a new and efficient technique based on packet pair to infer which layers to join. We evaluated PLM for a large variety of scenarios and show that it converges fast to the optimal link utilization, induces no loss to track the available bandwidth, has inter..

Pathological Behaviors for RLM and RLC

RLM [4] and RLC [7] are two well known receiver-driven cumulative layered multicast congestion control protocols. They both represent an indisputable advance in the area of congestion control for multimedia applications. However, there are very few studies that evaluate these protocols, and most of the time, these studies conclude that RLM and RLC perform reasonably well over a broad range of conditions. In this paper, we evaluate both RLM and RLC and show that they exhibit fundamental pathological behaviors. We explain in which context these pathological behaviors happen, why they are harmful, and why they are inherent to the protocols themselves and cannot be easily corrected. Our aim is to shed some light on the fundamental problems with these protocols 1 . Keywords: RLM, RLC, Pathological behaviors, Congestion Control, Multimedia, Multicast, Cumulative layers. 1 Introduction Multimedia applications will probably become some of the most popular applications in the Internet. On..

Beyond TCP-Friendliness: A New Paradigm for End-to-End Congestion Control

With the success of the Internet comes the deployment of an increasing number of applications that do not use TCP as a transport protocol. These applications can often improve their own performance by not being "TCP-friendly" and severely penalizing TCP streams. Also, designing these new applications to be "TCP-friendly" is often a difficult task. For these reasons, we propose a new paradigm for end-to-end congestion control (the FS paradigm) that relies on a Fair Scheduler network and assumes only selfish and non-collaborative end users. The flow isolation property of the FS paradigm is commonly agreed by the network community, however the lack of formalism of the FS paradigm hides fundamental properties. We rigorously define the properties of an ideal congestion control protocol and show that the FS paradigm allows to devise end-to-end congestion control protocols that meet almost all the properties of an ideal congestion control protocol. The FS paradigm is fully compatible with th..

Fast Convergence for Cumulative Layered Multicast Transmission Schemes

A major challenge in the Internet is to deliver live audio/video content with a good quality to large number of receivers. Multicast transmission and cumulative layered transmission are two mechanisms of interest to accomplish this task efficiently. However, protocols using these mechanisms suffer from low convergence time, lack of interprotocol fairness or TCP-fairness, and loss induced by the join experiments. In this paper we define and investigate the properties of a new multicast congestion control protocol for audio /video applications based on a cumulative layered multicast transmission. The protocol uses Packet Pair to discover the available bandwidth. It converges in the order of one second to the optimal link utilization, induces no loss to discover the available bandwidth, has inter-protocol fairness and TCP-fairness, and scales with the number of receivers and the number of sessions. Keywords: Congestion Control, Multicast, Capacity inference, Cumulative layers, Pa..