LJMU Research Online Yang, P, Fan, Q, Yin, H, Min, G, Luo, Y, Lyu, Y, Huang, H and Jiao, L Video Delivery Networks: Challenges, Solutions and Future Directions http://researchonline.ljmu.ac.uk/id/eprint/6324/ Article Citation (please note it is advisable to refer to the publisher’s version if you intend to cite from this work) Yang, P, Fan, Q, Yin, H, Min, G, Luo, Y, Lyu, Y, Huang, H and Jiao, L (2017) Video Delivery Networks: Challenges, Solutions and Future Directions. Computers and Electrical Engineering, 66. pp. 332-341. ISSN 0045-7906 LJMU has developed LJMU Research Online for users to access the research output of the University more effectively. Copyright © and Moral Rights for the papers on this site are retained by the individual authors and/or other copyright owners. Users may download and/or print one copy of any article(s) in LJMU Research Online to facilitate their private study or for non-commercial research. You may not engage in further distribution of the material or use it for any profit-making activities or any commercial gain. The version presented here may differ from the published version or from the version of the record. Please see the repository URL above for details on accessing the published version and note that access may require a subscription. For more information please contact [email protected] http://researchonline.ljmu.ac.uk/ Video Delivery Networks: Challenges, Solutions and Future Directions Qilin Fan1, Hao Yin1, Geyong Min2, Po Yang3, Yan Luo4, Yongqiang Lyu1, Haojun Huang5 and Libo Jiao1 1Research Institute of Information Technology (RIIT), Tsinghua University 2Department of Mathematics and Computer Science, University of Exeter 3Department of Computer Science, Liverpool John Moores University 4Department of Electrical and Computer Engineering, University of Massachusetts Lowell 5Department of Communication Engineering, Wuhan University ABSTRACT ing higher definition video streams, requesting more and Internet video ecosystems are faced with the increasing re- more bandwidth. The Cisco predicts that video con- quirements in versatile applications, ubiquitous consump- sumption will amount to 82% of the global consumer tion and freedom of creation and sharing, in which the user traffic in 2020 [1]. In conjunction with these growing experience for high-quality services has become more and traffic volumes, users’ expectations of high quality of more important. Internet is also under tremendous pres- experience (e.g., high-definition video, low re-bu↵ering, sure due to the exponential growth in video consumption. low startup delays) are continuously increasing [2]. Video providers have been using content delivery networks Content Delivery Networks (CDNs) have been playing (CDNs) to deliver high-quality video services. However, the a critical role in content hosting, orchestration, mashup, new features in video generation and consumption require transport, and edge access. Today, video providers rely CDN to address the scalability, quality of service and flex- on CDNs, such as Akamai and Limelight to serve video ibility challenges. As a result, we need to rethink future content across di↵erent geographical locations. However, CDN for sustainable video delivery. To this end, we give with the new characteristics of Internet video generation an overview for the Internet video ecosystem evolution. We and consumption, the architecture of today’s HTTP- survey the existing video delivery solutions from the per- based CDN is being stressed [3]. spective of economic relationships, algorithms, mechanisms As a result, there is a strong call for rethinking future and architectures. At the end of the article, we propose a evolution for sustainable video delivery. The state of data-driven information plane for video delivery network as the art in video delivery network has experienced a the future direction and discuss two case studies to demon- major boost in recent years, measured in the number of strate its necessity. publications and industrial groups focused on the topic. Diverse interests have led to heterogeneous, fragmented Keywords landscapes. In this article, we give a comprehensive review and analysis on video delivery network, focusing Video Delivery Network, Scalability, Quality of Ser- on the major obstacles in the way of further progress vice, Cloud computing, Data-Driven, Information Plane and suggesting possible future direction. The rest of the article is organized as follows. We 1. INTRODUCTION firstly give an overview of both the evolution of Inter- Video is a kind of important media for communication net video ecosystem and the key challenges to video and entertainment. In the past decade, the consump- delivery network in new personalization phase. After a tion of video contents changed from o✏ine viewing to brief summary on the surveys in this field, we illustrate online streaming, which imposed stringent requirements how existing approaches work to address parts of chal- on the network latency and throughput of video delivery lenges from the perspective of economic relationships, network. Internet video ecosystem has experienced new algorithms, mechanisms and architectures. Finally, we characteristics accordingly: (1) the diversity of video suggest constructing data-driven multidimensional in- applications, such as online streaming (e.g., IPTV and formation plane for video delivery network as future Netflix), and real-time video conferencing (e.g., Skype), research trend and conclude the article. (2) the ubiquitous video consumption by users who watch videos wherever they are and whenever they can; and (3) the freedom in the creating, distributing and sharing 2. VIDEO DELIVERY NETWORK: EVOLU- of user generated video contents through online video TION AND CHALLENGES services such as YouTube, Vimeo or Hulu. The situation Figure 1 shows the evolution of video ecosystem expe- is further deteriorated by the emerging trends of adopt- rienced several important phases in the last two decades. bu↵ering ratio reduces user engagement by 3 minutes in 1.#Streaming## 2.#Web#Video# 3.#Personaliza9on# Phase# Phase Phase# 2010 but 6 minutes in 2012. Therefore, video delivery !Simple(video(playback( -Integrated(with(Web(browser( !UGC,(SNS(consumpKon( service providers must keep improving server-side and !Proprietary(protocols( !RTMP(protocol( !MulKple(devices(and(apps( !Streaming(technology( !CDN,(P2P(technology(( !HTTP(streaming(protocol( network-level performance for better QoS. !Cloud(compuKng,(SDN,((((( data!driven,(mobile…( 3) High flexibility: Video consumption has shifted technology((( ( dramatically from a relatively predictive and controlled model to a highly dynamic mode, such as the large traffic spikes during online live and on-demand events. Streaming large live videos and popular on-demand ti- tles can cause significant network congestion leading to 1995 2004 2005 2011 Timeline poor subscriber experience. Traditional CDNs, however, are statically deployed, and their centralized redirection Figure 1: Evolution of Internet video ecosystem. mechanisms are not good for dynamic adjustment, which results in performance penalties. On the other hand, traditional CDNs were horizontal - designed to deliver In the mid-1990s, the Internet boosted from a text-based all forms of content by the same mechanism across all system to a multimedia-contained system. The repre- user categories. The flexible service depending on di↵er- sentative streaming technique changed the way videos ent business models require new CDNs that should be that are transmitted over the Internet, from the time- vertically customized according to di↵erent content and consuming downloads to real-time viewing. In 2005, user requirements. Adobe system acquired the flash player which was origi- nally developed by Macromedia, and flash soon became the de-facto standard for web-based streaming video 3. EXISTING SOLUTIONS (over RTMP) in this wave when videos explosively trans- To address the aforementioned challenges, a range of mitted across the Internet along with widespread broad- approaches were proposed in recent years. We survey the band access. Meanwhile, CDN and Peer-to-Peer (P2P) existing methods and classify them into four categories technologies emerged with the tide of the times. according to the challenge type the approach focused Since 2011, the portable devices with cameras have on and the perspective from which the approach solved become more and more ubiquitous, which enable users (shown in table 1). conveniently create and share videos. Users are increas- ingly demanding content on their terms - any content, 3.1 Cooperation between stakeholders any time, any device, any place. In addition, another The stakeholders in video delivery network ecosystem key driver to the rapid explosion of streaming video was can be grouped into the client, CDN, Internet Service the technical shift from specialized streaming protocols Provider (ISP), and Content Provider (CP). CP has a such as RTMP to HTTP chunk-based streaming proto- central database of content and pays CDN for content cols. The use of commodity service greatly decreases delivery service. The CDN is an overlay network that the barrier of access entry by allowing video providers to o↵ers additional value to the basic Internet content utilize the existing HTTP-based CDN infrastructures in delivery. It pays for transit service provided by ISP. delivering videos to wide audiences. New applications, Client pays ISP for network access and pays CP for devices and protocols not