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Content Delivery Network - CDN
- 1. Mojtaba HOUSHMAND IT‐VAS SolutionsTelecommunication – Consultant Mojtaba.houshmand@gmail.com Dec – 2017 Version 1.0 Content Delivery Network “CDN”
- 2. Content Outline • ContentDelivery Network Overview ---------------------------------> 3 • Content Delivery Network Architecture -----------------------------> 21 • Content Delivery Management ----------------------------------------> 30 • CDN Services & Functionalities ----------------------------------------> 34 • CDN Schemes ---------------------------------------------------------------> 52 • CDN Protocols --------------------------------------------------------------> 59 • CDNs vs. Caches ------------------------------------------------------------> 61 • CDN Revenue Sharing Model -------------------------------------------> 62 • Future Of CDN --------------------------------------------------------------> 64 • Known CDN Platforms ----------------------------------------------------> 65 • Case Study: Akamai Technology ---------------------------------------> 66 • References -------------------------------------------------------------------> 68
- 3. Content Delivery NetworkOverview • Online Video Business Models • Distance Matters and Network Terminology • Static & Dynamic CDN • Content Delivery Network • CDN Terminology • Suitable Content for CDN
- 4. Online Video BusinessModels OVP, CMS, MVP, CDN Online Video Platform (OVP): • Come from website video services into the multiscreen arena • Publish video to the internet by offering an 'ingest once, publish anywhere' approach Have comprehensive offerings including: • Content Management System (CMS) that helps to: • Manage videos • Publish videos to social media • Advertising plug-ins that helps to: • Monetize content • Integration APIs for mid-large scale video distributors • Easily deliver videos to all devices • Famous Companies: Brightcove, Ooyala, and Kaltura
- 5. Online Video BusinessModels OVP, CMS, MVP, CDN Content Management System (CMS): • Handle the metadata required to ingest, manage and publish content as part of a Pay TV offering • Providing better support for rights that vary by geography and device-type • Focus on TV Everywhere services • Handle multiple assets based on codec or packaging format. • Famous Companies: thePlatform and KIT Digital
- 6. Online Video BusinessModels OVP, CMS, MVP, CDN Managed Video Platform (MVP): • Used by mobile operators and/or traditional Pay TV distributors • Can generally be integrated in-house by the operators • Can be used on a hosted basis by the operator from the vendor using a: • Software as a Service (SaaS) • Platform as a Service (PaaS) model. • Famous Companies: MobiTV and Quickplay
- 7. Online Video BusinessModels OVP, CMS, MVP, CDN Content Delivery Network (CDN): • Responsible for getting bits from place to face in an efficient, low- latency fashion • Standalone CDNs are facing competition from two directions: • Telcos and MSOs are building their own CDNs to minimize their bandwidth cost • backbone carriers such as Level3 and Tata are also looking at CDN as a value added service to their customers. • Famous Companies: Akamai and Limelight
- 8. Distance Matters Greater Distance= Slower Communication • Bits travel at a limited speed • Laws of physics – apply to all connections Greater Distance = More Routing Hops • Greater chance of losing packets • Slowest router in pat dictates speed • Routing path isn’t optimal
- 9. Some Network Terminology Latency •Upload: Time to get bit from client to server • Download: Time to get bit from server to client Round-Trip Time (RTT) • Upload Latency + Download Latency Packet Loss Ratio (PLR) • Average Percentage of Lost Packets Effective Bandwidth • Real Upload/Download Speed, after RTT & PLR
- 10. CDNs bring thedata closer Move data closer to users • Improve RTT & Effective Bandwidth Keep many Edge Servers Sample Scenario 1. User requests (http://cdn.any.ir/image.gif) 2. cdn.any.ir resolves to closest Edge Server 3. if not in cache, Edge fetches and caches file 4. Edge returns data from local cache 5. Closer Copy = Faster Download
- 11. Static vs. DynamicContent Cache means Static Data • Page Resources: Images, CSS, Javascript... • Larger Download For Dynamic Data, some CDNs offer: • Routing Optimization • Extremely short-term cache
- 12. Common Mistakes Stale Cache •Outdated copy on edge server Solution: Versioning Double Payments • Pay Hosting & CDN Bandwidth cost Solution: Separate domain for static, cache-able files CDN-Specific Frequently Check • Test your CDN • Look for cache-hit header • Check CDN cache-hit dashboards
- 13. Content Delivery Network •Is a collaborative collection of network element spanning the Internet. • Content are replicated over several mirrored Web Server. Why it is done? • To perform transparent and effective delivery of content to the end- user. • To over come the inherent limitations of the Internet in terms of QoS. • Improving the performance by maximizing the bandwidth, improving the accessibility.
- 14. Content Delivery Network Generationof CDN 1st Generation: Focused on Static or Dynamic Web Document 2nd Generation: Focused on Video and Audio Streaming such as Video-on-Demand (VoD) and Audio-on-Demand (AoD). Mechanism for: • Replicating content on multiple servers in the Internet. • Providing clients with a means to determine the servers that can deliver the content fastest.
- 15. Content Delivery Network Modelof Content Delivery Network It contains 2 parts: 1. Encoded media 2. Meta data Main entities in CDN systems are: 1. Content Provider 2. CDN provider 3. End-User
- 16. CDN: Basic Idea congested Notcongested original content Replica Replica Client
- 17. CDN Terminology • Content Anypublicly accessible combination of text, images, applets, frames, MP3, video, flash, virtual reality objects, etc. • Content Provider Any individual, organization, or company that has content that it wishes to make available to users. • Origin Server Content providers server , where the content is first uploaded. • Surrogate Server Content distributor’s server, where the replicated content is kept.
- 18. Players of thegame in CDN Content Provider H/W and S/W Vendor Content Distributor Hosting Provider Yahoo, MSNBC, CNN Cisco, Lucent, Inktomi, CacheFlow Akamai, Digital Island, AT&T Exodus
- 19.
- 20. Suitable Content forCDNs Content Suitable for CDNs • Images • High-volume e-commerce transactions (thanksgiving sale) • Streaming media (audio and video) (media events) • Java Applets • Virtual Reality Objects • Flash content Content NOT Suitable for CDNs • Personalized content (my.yahoo.com,…) • Dynamic Content • Secure Content
- 21. Content Delivery NetworkArchitecture • Architectural Component of CDN • Content Distribution Internet-working: CDI • Request Routing • Metrics
- 22. Architectural Component ofCDN 4 Main Component: 1. Original Server 2. Distribution System 3. Request Routing System 4. Account System
- 23. Architectural Component ofCDN Request Routing in CDN Environment
- 24. Content Distribution Internet-working:CDI • Interconnection of Content Networks – collaboration between caching proxies and CDNs, as well as between individual CDNs • Greater reach, larger scale, higher capacity, increased fault tolerance • Basic architecture involves gateways between various content networks
- 25. CDI: Architecture A Modelfor Content Inter-networking (CDI) RFC3466 Content Inter-networking (CDI) Scenarios RFC3570
- 26. Request Routing Mechanisms Bestsurrogate selected based on some metrics. Techniques • DNS based request routing • Content Modification (URL rewriting) • Anycast based • Transport-Layer Request-Routing • Application-Layer Request-Routing • TTP Redirection • CDN peering • Combination of multiple mechanisms
- 27. CDN: DNS basedRequest Routing Akamai DNS Local DNS Server 128.4.4.12 www.cnn.com 63.251.132.22 www.cnn.com Session 63.251.132.22 63.210.135.39surrogate surrogate www.cnn.com
- 28. Content Modification ... <img src="http://www.cdn.com /cnn/images/1.gif”> ... Index.html GETwww.cnn.com/index.html Index.html DNS query:cdn.com ? 64.236.24.28 Authoritative DNS server for cdn.com Local DNS serverClient CNN.com 64.236.24.28
- 29. Metrics Network Proximity (Surrogateto Client): • Network hops (traceroute) • Round Trip Time (RTT) • Internet mapping services (NetGeo, IDMaps) … Surrogate Load: • Number of active TCP connections • HTTP request arrival rate • Other OS metrics … Bandwidth Availability
- 30. Content Delivery Management •Site Delivery • Content Delivery Network Pricing/Billing
- 31. Content Delivery Management SiteDelivery Full site delivery vs. Partial Site Delivery Full Site Delivery: All the contents are delivered by the CDN (including HTML, images, and other objects). Partial Site delivery: Only images, streaming media and other bandwidth intensive objects delivered by the CDN.
- 32. Content Delivery Management ContentDelivery Network Pricing/Billing • Charging to the customer depend upon the content delivered to the end-user by their surrogate servers. • It support an account mechanism that collect and track client usage information. • The average cost of charging of CDN services is high • Important factor which influence in revenue generation are: 1. Bandwidth cost 2. Variation of traffic distribution 3. Size of content replicated over surrogate servers 4. Number of surrogate server 5. Reliability and Stability of the whole system
- 33. Content Delivery Management PricingModel Of CDN • Pricing Based On Aggregate Usage • Charging on Monthly basis that is 50TB/month • Percentile – Based Pricing • Pricing based on the 95th percentile of traffic CDN periodically samples the bandwidth usage of a subscribing content provider. It then computes the 95th percentile of usage at the end of the month and charges a price per Mbps based on the 95th percentile of usage.
- 34. CDN Services &Functionalities • Web Accelerator • Video Delivery • Media Streaming • Live Streaming • OTT • IPTV • Time Shifting • VoD • TV Catch-up • Video Transcoding • Load Balancing • Reporting & Analytics
- 35. CDN Services &Functionalities
- 36. CDN Services &Functionalities CDN services generally covered these aspects: • Storage and Management of Content • Distribution of Content among Edge Servers • Cache Management • Delivery of Encoded Media • Backup and Disaster Recovery Solutions • Monitoring and Performance
- 37. Website Accelerator • Mostweb publishers start serving their site with a hosting service. • With increase in traffic and geographically variance, don’t face difficulty in scaling and delivering satisfactory user experiences CDN will: • Speed the delivery of assets to visitors • Reduce the need to scale web infrastructure • Improve user experiences
- 38. Website Accelerator • DeliverHTML, CSS, Javascript, Ajax, images, video, and more • Rich proxy capabilities, including query string handling and custom header processing • Control over HTTP header responses • Rapid cache purging within the CDN • Customers retain full control of their content and have the ability to add, delete, rename, and update their own content • Supported Devices: Support for browsers on PCs, tablets, mobile devices, and set-top boxes • Supported Protocols: HTTP • Multi-format video delivery: HTTP, RTMP, RTSP • Support for authentication with customer origin • Support for reverting to a secondary origin in case the primary origin server is unavailable • Support for geo-blocking with directory-level control over
- 39. Video Delivery Content ownerscan deliver best possible video experience on websites and in applications • Start instantly • Play smoothly • Flexible configuration options • Advanced video features • Reporting & Analytics • Delivery of multiple bit-rates • Delivery control by region • Device supported • Flexible configurations for storage and delivery of videos
- 40. Media Streaming Streaming mediais multimedia that is constantly received by and presented to an end-user while being delivered by a provider. Streaming Situations: • Watch Digital Video Content • Listen to Digital Audio Content • No need to download before start to play Media Streaming Applications: • Flash: Adobe • SilverLight: Microsoft • HLS: Apple Popular Streaming Services: • Video Sharing Website: YouTube, Twitch and Mixer (Games) • Movie & TV Shows: Netflix • Music: Spotify and Apple Music
- 41. Live Streaming Live Streamingrefers to online streaming media simultaneously recorded and broadcast in real time to the viewer. Live stream services encompass a wide variety of topics, from social media to video games. With broad protocol, platform and device support, Live Broadcast enables you to reach your viewers worldwide and on a variety of platforms. Lifecasting or lifestreaming is a real-life activity facilitated by live streaming. Application: Instagram Live, Facebook Live, Periscope Video Game: XboxLive, PSLive, Twitch
- 42. Live Streaming Video SupportFeatures • DVR-Like Controls: pause, rewind, restart and jump to any point within a live broadcast • Configuration: Customer configurable CNAMEs • Multiple Bit-Rate Support • Secure Streaming • Encoders Supported • Output Protocols: HTTP, HLS, RTMP, RTMPE, RTMPTE, RTSP, and Silverlight. • Supported Devices: laptops, tablets, mobile devices, and set-top boxes • iOS devices, Android devices, Windows devices, • Resolutions: Support for up to 4K • Reporting & Analytic
- 43. Over The Top(OTT) Over the top (OTT) is an application or service that is able to provide a product over the Internet. This method bypasses traditional methods of distribution. Over the top services are mostly related to media and communication and are lower in cost when compared to traditional delivery methods. Hulu and Netflix that replaced regular TV providers and Skype that replaced long distance communication providers are examples of OTT. OTT Video • Access is controlled by the video distributor, through either an app or a separate OTT dongle or box, connected to a phone, PC or television set. • Remains the most popular OTT content. OTT Messaging • Is defined as instant messaging services • Alternative to text messaging services provided by a mobile network operator • OTT messaging Application: WhatsApp, Viber, WeChat, Skype and Facebook msg. OTT Voice Calling • Use open Internet communication protocols • For instance, as provided by Skype, WeChat, Viber, and WhatsApp
- 44. Internet Protocol TV(IPTV) Internet Protocol television (IPTV): • Deliver television content over Internet Protocol (IP) networks. • Offers the ability to stream the source media continuously. • Play almost immediately the content by client media player (such as a TV channel). • Widely deploy in subscriber-based telecommunications networks with high-speed access channels into end-user premises via set-top boxes • Use for media delivery around corporate and private networks. IPTV services may be classified into three main groups: • Live Television and Live Media • Time-Shifted Media: • Catch-up TV (replays a TV show that was broadcast hours or days ago) • Start-over TV (replays the current TV show from its beginning); • Video on Demand (VoD): • browse and view items in a stored media catalog.
- 45. Video on Demand Videoon Demand (Display) (VoD) • Allow users to select and watch/listen to video or audio content • IPTV technology is often used to bring VoD to televisions and personal computers. Development of Video on Demand services: • The video that was selected is transmitted through real-time streaming protocol. • While TV uses traditional broadcast technology, VoD uses unicast transmission. • Development of file sharing software. Catch-up TV • Watch TV shows though their VoD service hours or even days after the original television broadcast. • Watch a program in free time
- 46. Video on Demand VoDvs. OTT Service: OTT: OTT can be related to a product or service VoD: VoD is only related to videos and presentations Channels: OTT: A range of channels are available to be viewed. VoD: The user can only view selected videos and this service is premium in nature. Quality: OTT: OTT is more professional in managing, monetizing and distributing video content. VoD : VoD provides an uncompromised video experience.
- 47. Video Transcoding Video Transcoding,also called video encoding, is the process that converts a video file from one format to another, to make videos viewable across different platforms and devices. • Direct digital-to-digital conversion of one encoding to another • such as for movie data files (e.g., PAL, SECAM, NTSC) • audio files (e.g., MP3, WAV) • character encoding (e.g., UTF-8, ISO/IEC 8859). Done in cases where a target device (or workflow): • Does not support the format • Has limited storage capacity that mandates a reduced file size • Convert incompatible or obsolete data to a better-supported or modern format. One may also re-encode data in the same format, for a number of reasons: • Editing • Lower Bit Rate • Image Scaling
- 48. Multiple video formats Pushonce publish many
- 49. Load Balancing Server LoadBalancing (SLB): • A Device between the customers and multiple instances of your hardware (Real Server) • A single, virtual server front-end to the customers of the service • Allows to give your customers a single name or IP address for your service (Virtual Server IP address: VIP) • Uses the real servers' load and health check information
- 50. Load Balancing Global ServerLoad Balancer (GSLB): • Is a wide-area load balancer also known as a Global Server Load Balancer (GSLB) • Uses DNS as the traffic management mechanism • Puts intelligence into the DNS resolution process • Monitors site availability and performance Static load balancing methods Dynamic load balancing methods Drop Packet Completion Rate Fallback IP CPU Global Availability Hops Round Robin Kilobytes/Second Ratio Round Trip Time Static Persist Packet Rate Topology Quality of Service
- 51.
- 52. CDN Schemes • WebCaching • Content Distribution Networks of Cache
- 53. CDN Schemes Server Farm L4-L7Switch Does load balancing Internet Server-1 Server-2 Server-n Requests = R Requests = R/n
- 54. CDN Schemes Client Networkwithout a Web Cache 1.5 Mbps access link 100 Mbps LAN Internet delay=2 sec 15 requests/sec Avg. object size = 100 Kbits Access delay = ΔLAN = 15x100 Kb/100 Mbps = 0.015 Δaccess link = 15x100 Kb/1.5 Mbps = 1 Δ – traffic intensity HUGE Total delay = Internet delay + Access delay
- 55. CDN Schemes Web Cache:Basic operation GET Object present ? No-> Fetch Object Yes-> Send Object GET RESPONSE Cache RESPONSE GET RESPONSE Client 1 Web server
- 56. CDN Schemes Web Cache 1.5Mbps access link 100 Mbps LAN Internet delay=2 Sec delay = tens of milliseconds ΔAL = 0.6 Δ – traffic intensity Institutional cache Hit rate = 0.4 Total delay = (2 + .01) x 0.6 = 1.2 Sec
- 57. CDN Schemes Content DistributionNetwork of Caches Web serverWeb server Proactive replication Parent Child 1 Child 2
- 58. CDN Schemes Problems withdiscussed approaches: Server farms and Caching proxies • Server farms do nothing about problems due to network congestion, or to improve latency issues due to the network • Caching proxies serve only their clients, not all users on the Internet • Content providers (say, Web servers) cannot rely on existence and correct implementation of caching proxies • Accounting issues with caching proxies. For instance, www.cnn.com needs to know the number of hits to the advertisements displayed on the webpage.
- 59. CDN Protocols Relating tocontent delivery and CDNs, HTTP/1.1 includes cache control mechanisms In the case of a CDN, the use of HTTPS is generally accompanied by a redirection to a secure server from a surrogate Common famous applications are Windows Media Player, RealPlayer and QuickTime using plugins for the web browser in order to embed the streaming inside HTML. Timestamps for synchronization are introduced via RTP, and add-on features such as Video-on- Demand is provided by RTSP Cache Management Protocols: • Internet Cache Protocol (ICP): Squid, Microsoft Proxy, Volera, Cisco Cache Engine • HyperText Caching Protocol (HTCP) • Cache Array Routing Protocol (CARP) and Cache Digests. UniCast Streams: for a small number of surrogates the origin site sends data directly to all of them. Application Layer Multicast (ALM) protocols: can be classified as tree-first or mesh-first approach.
- 60. CDN Protocols Media Streamingcommon Protocols: Audio Streaming: audio coding format such as MP3, Vorbis, AAC or Opus. Video Streaming: Video coding formats include H.264, HEVC, VP8 or VP9. Encoded audio and video streams are assembled in a container "bitstream" such as MP4, FLV, WebM, ASF or ISMA. The bitstream is using a transport protocol to enable adaptive bitrate streaming over HTTP: • Adobe's RTMP or RTP, Adobe's HDS • Apple's HLS • Microsoft's Smooth Streaming • MPEG-DASH Stream Media over networks: • Real-time Streaming Protocol (RTSP) • Real-time Transport Protocol (RTP) • Real-time Transport Control Protocol (RTCP)
- 61. CDN vs. CachingProxies Caching Proxies CDN Used by ISP to reduce bandwidth consumption Used by Content Providers to increase QoS Operate Reactively Operate Proactively Caching proxies cater to their users (web clients) and not to content providers (web servers) CDNs cater to the content providers (web servers) and clients Caching proxies do not give control of the content to the content providers CDNs do
- 62. CDN Revenue SharingModel Buy Model Network operator pays $1.8 billion in CDN fees over the six-year period.
- 63. Model of RevenueSharing Build Model Network operator has a total capital expenditure of $51 million over a six-year period.
- 64. Future OF ContentDelivery Network Global Content Delivery Network revenue Video:- $3.8 billion US
- 65.
- 66. Case Study: AkamaiTechnologies • Leader in providing a secure, outsourced e-business infrastructure services and software. • Covers 85% of the market. 20,000 servers in nearly 1,000 networks in 71 countries. It handles 20% of total Internet traffic today. • Developed a set of breakthrough algorithms for intelligently routing and replicating content over a large network of distributed servers.
- 67. Akamai Services Core Features: •Alerts • Property Manager • Luna Control Center • Content Control Interfaces Media Delivery: • Adaptive Media Delivery • Media Services Live • Media Security Policy • Download Delivery • Media Analytics • Object Delivery • Media Services On Demand • Infinite Media Products
- 68. References Content Delivery Networks Wikipedia:The Free Encyclopedia https://www.wikipedia.org/ TATA www.tatadocomo.com/business Akamai https://www.akamai.com/ Blaze: Intelligent & Optimization Front-End Optimization Series University of Delaware Girish Borkar: Department of Computer and Information Sciences MIT School Of Telecom Shiv Kumar Pandey: Telecom Technologies Courses
- 69.