دانلود رایگان مقاله انگلیسی بررسی شبکه های تحویل محتوا با همکاری - الزویر 2017

Abstract

Peer-assisted content delivery networks have recently emerged as an economically viable alternative to traditional content delivery approaches: the feasibility studies conducted for several large content providers suggested a remarkable potential of peer-assisted content delivery networks to reduce the burden of user requests on content delivery servers and several commercial peer-assisted deployments have been recently introduced. Yet there are many technical and commercial challenges which question the future of peer-assisted solutions in industrial settings. This includes among others unreliability of peer-to-peer networks, the lack of incentives for peers’ participation, and copyright issues. In this paper, we carefully review and systematize this ongoing debate around the future of peer-assisted networks and propose a novel taxonomy to characterize the research and industrial efforts in the area. To this end, we conduct a comprehensive survey of the last decade in the peer-assisted content delivery research and devise a novel taxonomy to characterize the identified challenges and the respective proposed solutions in the literature. Our survey includes a thorough review of the three very large scale feasibility studies conducted for BBC iPlayer, MSN Video and Conviva, five large commercial peer-assisted CDNs - Kankan, LiveSky, Akamai NetSession, Spotify, Tudou - and a vast scope of technical papers. We focus both on technical challenges in deploying peer-assisted solutions and also on non-technical challenges caused due to heterogeneity in user access patterns and distribution of resources among users as well as commercial feasibility related challenges attributed to the necessity of accounting for the interests and incentives of Internet Service Providers, End-Users and Content Providers. The results of our study suggest that many of technical challenges for implementing peer-assisted content delivery networks on an industrial scale have been already addressed in the literature, whereas a problem of finding economically viable solutions to incentivize participation in peer-assisted schemes remains an open issue to a large extent. Furthermore, the emerging Internet of Things (IoT) is expected to enable expansion of conventional CDNs to a broader network of connected devices through machine to machine communication.

 Conclusion and Vision on Direction of Research in the Future

In this paper, we present a comprehensive survey of the peer-assisted content delivery networks (PA-CDNs). We investigated the concept of merging two complementary technologies, key benefits in terms of the traffic saving, challenges and future research directions. Our analysis captures a decade-long history of research and industrial efforts in the field, including three feasibility studies for the large video-on-demand platforms (BBC iPlayer, MSN Video, Conviva), a review of five different commercial PA-CDNs (Kankan, LiveSky, Akamai NetSession, Spotify and Tudou) and a vast scope of technical and modeling papers. From the analysis of the literature, we identify three groups of challenging factors for industrial implementation of peerassisted CDNs, namely, heterogeneity and scale challenges, technical challenges and commercial feasibility challenges, which form a taxonomy for our survey. The results of our survey suggest a significant potential of peer-assisted content delivery in reducing infrastructural costs for content providers and CDNs: from around 50% to 88% of all consumer traffic can be offloaded to peers as reported by various feasibility studies. Moreover, our analysis of the five large commercial systems suggests that many technical and feasibility concerns with respect to deployment of PA-CDNs in production systems have been already addressed by the existing peer-assisted CDN solutions. Among others, significant research efforts have been focused on solving quality of service issues, where bootstrapping video streams from edge servers and an effective management of P2P swarms have been proposed to solve the startup and playback latencies, respectively.