Content Delivery Networks

9 Key excerpts on "Content Delivery Networks"

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  eBook - PDF

  A Practical Guide to Content Delivery Networks

  • Gilbert Held(Author)
  • 2010(Publication Date)
  • CRC Press

    (Publisher)

  1 1 I NTRODUCTION TO C ONTENT D ELIVERY N ETWORKING The purpose of any introductory chapter is to acquaint readers with the topic or topics covered by a book, and this chapter is no exception. Commencing with a definition of a content delivery network (CDN), we will describe and discuss its evolution. In doing so, we will examine several types of networking technologies that were devel-oped to deliver specific types of content as well as the rationale for the development of the modern content delivery network. 1.1 The Modern Content Delivery Network The modern content delivery network can be defined very simply as follows: A content delivery network represents a group of geo-graphically dispersed servers deployed to facilitate the distribution of information generated by Web publishers in a timely and efficient manner. Of course, this definition does not mention the capacity of dispersed servers. Less than a decade ago, the transfer of digitized video was in its infancy. Today, YouTube and other sites are making the use of video commonplace. When you add in the growth of smart phones and their data delivery—which, according to an article appearing in the Technology section of the October 30, 2009, edition of the Wall Street Journal , entitled “Unraveling In-Building Wireless Networks,” AT&T experienced a growth of data on its network that expanded by 4,932% between the third quarter of 2006 and the second quarter of 2009—the capacity of servers becomes extremely impor-tant. This is a subject we will revisit numerous times in this book. Although the prior definition of a content delivery network is simplistic, it tells us a significant amount of information about what a CDN represents. That is, a CDN is a group of servers that facili-tate the distribution of information generated by Web publishers in a 2 A PRACTICAL GUIDE TO Content Delivery Networks timely and efficient manner.

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  eBook - ePub

  Web Performance Optimization

  A Practical Approach

  • Sufyan bin Uzayr(Author)
  • 2022(Publication Date)
  • CRC Press

    (Publisher)

  Everyone talks a good deal about CDNs nowadays, and the options are plentiful. But what are these CDNs, and how can we make the most out of them as far as web performance optimization is concerned?

  What Is a Content Delivery Network?

  A CDN is a conglomerate of geographically distributed servers and data centers for spatial distribution of data to users around the world.

  Here is how Wikipedia describes a CDN:1

  A content delivery network, or content distribution network (CDN), is a geographically distributed network of proxy servers and their data centers. The goal is to provide high availability and performance by distributing the service spatially relative to end users.

  In simple words, a CDN works by putting together a range of servers and data centers around the world. Now, as and when a given user accesses a web page, the CDN fetches it from the delivery network or data center closer in proximity to the user's geographical location.

  Naturally, this cuts down the latency and the time required in transmission of data between geographically distant locations. As such, CDNs can help boost web speed by keeping a cluster of servers and data centers and using geographical location to their advantage.

  1 See: https://en.wikipedia.org/​wiki/​Content_delivery_network , last edited on November 26, 2021

  This, of course, is not the only advantage that a CDN brings to the table. CDNs can and have proven especially useful when it comes to website security and hardening, as a CDN can keep spam bots and DDoS attacks at bay, if properly configured.

  We will be coming to the advantages that CDNs have to offer in a short while. Before that, let us first understand how a CDN works.

  How Do Content Delivery Networks Work?

  We know that a CDN, in itself, is a wide network of various servers and hardware platforms, each is marked by a distinct geographical location. Now, considering the fact that nearly every website on the Internet is made up of HTML, CSS, JavaScript, and other multimedia assets, a CDN leverages this fact and creates handy copies of such assets.

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  eBook - ePub

  Advanced Content Delivery, Streaming, and Cloud Services

  • Mukaddim Pathan, Ramesh K. Sitaraman, Dom Robinson, Mukaddim Pathan, Ramesh K. Sitaraman, Dom Robinson(Authors)
  • 2014(Publication Date)
  • Wiley-IEEE Press

    (Publisher)

  Part I CDN and Media Streaming Basics Chapter 1 Cloud-Based Content Delivery and Streaming Mukaddim Pathan Telstra Corporation Ltd., Melbourne, Victoria, Australia 1.1 Introduction Over the last decade, end-users have been increasingly using the Internet to access not only typical websites but also high definition (HD) video and rich media content. While accessing the Web, end-users expect high bandwidth, improved performance, and low latency for the delivered content. End-users' requirements of high quality, consistent, dependable, responsive viewer experience can be characterized by faster loading Web pages, quick channel changes and downloads, fast-start video, and quality of experience (QoE) in mobile devices. Similarly, content providers require an efficient content delivery mechanism to increase growth and scale, reliability and performance, and engagement and reach, while decreasing cost, risk, and network load. Content Delivery Networks (CDNs) [1–4] improve websites, streaming, and download performance of Internet content by end-users while reducing the cost to serve for content providers. A CDN is a collaborative collection of network elements spanning the Internet, where content is replicated over mirrored Web servers (i.e., point of presence (PoP), edge or replica servers), located at the edge of the Internet service providers' (ISPs') networks to which end-users are connected. As shown in Figure 1.1, content is served into the CDN once, then content is delivered to end-users from the edge servers rather than serving each individual request directly from the content provider's origin server. Nowadays, CDNs are a prerequisite for delivering quality online experience for live, linear, and on-demand delivery of website and media content

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  eBook - ePub

  The Technology of Video and Audio Streaming

  • David Austerberry(Author)
  • 2013(Publication Date)
  • Routledge

    (Publisher)

  One family of solutions is the Content Delivery Network (CDN). These were first developed for the delivery of conventional HTML pages and file downloads. The CDN also can be used to improve the streaming experience, while giving more efficient utilization of the intervening network. With a CDN the viewer should see less of the stalled streams that mark the delivery of content over long-haul networks. The service provider also benefits, as less bandwidth is required to connect to the Internet backbone.

  Content Delivery Networks

  The basic premises of the CDN are to serve content closer to the user rather than across the Internet and to intelligently direct the routes taken by the data packets that make up the stream. The former is called edge serving. If you are not using a CDN to view streaming media, a request for content traverses the Internet from network to network; it can pass through as many as 20 routers. The content data then returns, possibly along a different path through another 20 routers. At each stage packets can be lost or delayed, but streaming requires a regular data delivery rate to the player. Any congestion is going to result in the often-seen picture freezes and loss of the soundtrack.

  The CDN avoids the effects of this transit congestion by serving the content from the user’s point-of-presence (POP), at the edge of the Internet. The CDN places special edge servers at the ISP providing your local point-of-presence. The CDN then uses a control network overlaid on the Internet to respond to requests for clips and to manage the delivery of clips from the origin server to the edge servers.

  The CDN has four main components to help provide high-quality streams local to the user:

  • Intelligent routing
  • Edge caching of content
  • Proxy serving
  • Splitting of live webcasts

  Figure 15.2 Serving from the origin.

  Intelligent or smart routing is an overlay above the regular Internet routing. Requests to the origin server for media clips are intercepted and redirected to the nearest available edge server. The smart routing also delivers content from the origin server to the edge server by the best route, bypassing congested links.

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  eBook - ePub

  Quality of Experience for Multimedia

  Application to Content Delivery Network Architecture

  • Abdelhamid Mellouk, Hai Anh Tran, Said Hoceini(Authors)
  • 2013(Publication Date)
  • Wiley-ISTE

    (Publisher)

  Chapter 3

  Content Distribution Network

  In this chapter, first, we present the general architecture of a content distribution network (CDN) system with its components and functions. Then, we describe in detail its two main layers: the routing layer and the meta-routing layer.

  3.1. Motivation

  Nowadays, the demand for content on the Internet is increasing rapidly. This needs an efficient and scalable content distribution solution. Implementing multiple servers placed at geographically distributed locations replaces using single-server schemes. The general idea of this evolution is to bring the servers geographically closer to clients. This new architecture, called CDN, will improve the performance of the system, reduce network load and provide better fault tolerance. Currently, there are many successful CDN providers such as Akamai [AKA 98] and Digital Island [DIG 96].

  The general operation mechanism of a CDN service is depicted in Figure 3.1 . When a customer (e.g. a Website and VoD service) subscribes to a CDN service, the customer provides data to the CDN provider. The latter will implement a distribution network in using replica server scheme. More precisely, a CDN provider replicates the content data from the origin server of the customer to the replica servers scattered over the Internet. The operation mechanism of a user’s request is described step by step as follows. First, the end user sends a request to the Website (step 1). Then, the Website forwards the request to the CDN service (step 2). Finally, the CDN provider uses several mechanisms to select the most appropriate server with which to serve the end user (step 3).

  Figure 3.1.

  CDN service

  Figure 3.2

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  eBook - ePub

  Media Networks

  Architectures, Applications, and Standards

  • Hassnaa Moustafa, Sherali Zeadally, Hassnaa Moustafa, Sherali Zeadally(Authors)
  • 2016(Publication Date)
  • CRC Press

    (Publisher)

  † protocol standard, as early as in 1997. HTTP standards indeed enable caching proxies to deliver content on behalf of origin servers, to improve performance, save network resources, and enforce traffic filtering policies. For example, caching proxies have been deployed for more than 15 years at the edges of campus networks. The servers that hold the replicated content are often called surrogates, or cache nodes.

  Today, as the Internet has become the support of a much wider diversity of services, CDNs address many different types of content. In particular, video traffic is subject to stringent quality-of-service (QoS) constraints and requires massive amount of network resources. Therefore, most large video providers rely on CDNs for delivering their content through streaming, video on demand, and so on. In addition, more and more people use the Internet to buy or sell products and services. As customers are sensible to the loading time of Web-shops, Internet sellers use CDNs to accelerate their websites (dynamic site acceleration (DSA)). Last but not least, CDN providers have developed application-specific features to accelerate enterprise applications such as Web services, in-network databases, cloud services, and so on.

  10.2.2 Definition of CDN

  In this section, we compare CDN to other content delivery techniques, such as P2P, multicast, and transparent caching.

  10.2.2.1 Peer-to-Peer

  Peer-to-peer (P2P) follows the same rationale as CDN; that is, it uses more distributed servers than in the typical client−server model. However, P2P requires littler infrastructure in the network than CDNs, because it uses the end-user’s devices as content servers, whereas CDNs rely on in-network servers. In addition, CDN typically does not require any modification to the end-user’s configuration, whereas P2P relies on the installation of client software by the end user.

  Interestingly, some CDNs use P2P technologies to optimize the distribution of content among the cache nodes, and to take advantage of end-user’s devices for improving content delivery performance. For instance, Akamai has implemented a client-side cache called NetSession.

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  eBook - ePub

  Digital Video Distribution in Broadband, Television, Mobile and Converged Networks

  Trends, Challenges and Solutions

  • Sanjoy Paul(Author)
  • 2011(Publication Date)
  • Wiley

    (Publisher)

  Content distribution network service providers create an overlay net work of servers that are strategically deployed in the Internet. Content distribution networks are overlay networks because these networks are composed of mirror servers (also called replica servers) which are nothing but end systems (that terminate TCP/IP connections). Mirror servers sitting on top of the Internet leverage the network-level service of the Internet. Mirror servers are placed in the data centers of the Internet service providers (ISPs). Thus a CDN consists of an overlay network of large number of mirror servers distributed over the Internet. The objective of having geographically distributed mirror servers is to be able to serve the clients from the “nearest” mirror server in order to mitigate the effects of propagation delay, transmission delay and queuing delay. In the context of video streaming, jitter is likely to be reduced as the number of routers that are instrumental in injecting jitter is significantly reduced between the client and the mirror server from which video is streamed. For exactly the same reason the probability of packet loss is also reduced. The overall user experience is thus significantly improved. There are some subtle points that need to be understood and appreciated in the context of CDN. First, CDN is a “shared” infrastructure in that the mirror servers belonging to a CDN service provider are usually “shared” between multiple content providers. These content providers are the customers of the CDN service providers. Second, the value provided to the content providers by the CDN service providers is measured by the amount of content (GB) downloaded from the mirror servers and the peak bandwidth needed to serve the content from the mirror servers, because in the absence of CDN service provider, their own infrastructure would have to do the same. A representative deployment of CDN is shown in Figure 7.1

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  eBook - ePub

  User-Centric and Information-Centric Networking and Services

  Access Networks, Storage and Cloud Perspective

  • M. Bala Krishna(Author)
  • 2019(Publication Date)
  • CRC Press

    (Publisher)

  Nowadays content delivery, with an emphasis on video streaming, is the major source of bandwidth consumption on the Internet, so efficient and effective content distribution is a key aspect to deploy bandwidth demanding services at large scales. As a solution, Content Delivery Networks (CDNs) are being deployed and offered to content providers and carriers as cost saving solutions, but they add undesired complexity to end-to-end operations and content state management, becoming too closed and hard to adapt to new workflows. Those solutions are also limited by the strict environment established by underlying architectures, which are typically tied to Internet Protocol (IP) and conducting to the ossification of networks.

  Guided by these limitations of the current network architectures, the major proposals towards the Future Internet (FI) have focused on providing an evolutive or disruptive path to deliver the best service to final users. On the one hand, we have the cases of Location/ID Separation Protocol (LISP) [1 ,2 ], Host Identity Protocol (HIP) [3 ], Heterogeneity Inclusion and Mobility Adaptation through Locator ID Separation (HIMALIS) [4 ], and Mobile Oriented Future Internet (MOFI) [5 ], which provide different solutions to separate identifiers and locators in the network in order to provide enhanced scalability and security.

  On the other hand, in order to resolve part of the limitations exposed by CDNs and thus break the ossification of networks in content distribution, the Information-Centric Networking (ICN) paradigm has proliferated to exploit the possibilities that intermediate network elements have to achieve efficient and effective content delivery. Within ICN we find some outstanding solutions, such as NDN/CCN [6 ], PURSUIT [7 ], and Network of Information (NetInf) [8 ], which provide mechanisms to change the way content is represented in the network traffic and intermediate elements.

  Although all architecture proposals have represented a renovation of the network to provide specific solutions to specific problems, most of them are clean-slate, so they require a jettisoning of the current infrastructures in order to support the building of their solutions. However, there is a distinctive approach that opens evolutive paths and allows the introduction of new mechanisms to current networks. It is the SDN initiative [9

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  ASP Configuration Handbook

  • Syngress(Author)
  • 2001(Publication Date)
  • Syngress

    (Publisher)

  What Is Load Balancing? Load balancing is the one of the most commonly used techniques to improve response time of content on the Internet. Several Web servers are configured to share the load of the processes. A side benefit of load balancing is that it offers fault tolerance, due to the nature of using multiple servers. What Is Content Routing? Content routing can be used to handle mission-critical Web sites, by providing fast response times.Web pages for these sites are replicated to diverse data centers at different geographical locations.This permits end users to access these pages quickly from multiple sources.This technology has enabled one of the newest and possibly most powerful technologies for the future of the Internet: Content Delivery Networks (CDN).This combines traditional routing and switching intelligence with content-aware technology (at a packet level), which is located at service provider distribution areas or enterprise data centers. Web Caching and How It Works Bandwidth shortage is only one of the obstacles that contribute to the slow response time of Web-based content. Building up bandwidth connection will not necessarily solve network latency or slow Web server access.Web caching was created in order to address these problems.The intent of caching is to move Web content as close to the end users as possible for quick access to improve the cus-tomers’ satisfaction levels, and gives your ASP the competitive advantage. Performance Enhancement Technologies • Chapter 4 189 190 Chapter 4 • Performance Enhancement Technologies What Is Data Caching? As you have probably seen, data caching is a highly efficient technology that is already implemented in many areas of your network as well as in the Enterprise networks.

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