1.Encoded media include static(content that are not change is called static content example:-www.google.com), dynamic and continuous media data( example:- audio, video, document, images and web pages).2. Metadata is the content description that allows identiﬁcation, discovery, and management of multimedia data, and facilitates its interpretation. Content can be pre-recorded or retrieved from live sources; it can be persistent or transient data within the system .A content provider or customer is one who delegates the Uniform Resource Locator (URL) name space of the Web objects to be distributed. The origin server of the content provider holds those objects. A CDN provider is a proprietary organization or company that provides infrastructure facilities to content providers in order to deliver content in a timely and reliable manner. End users or clients are the entities who access content from the content provider’s Web site. CDN providers use caching and/or replica servers located in different geographical locations to replicate content. CDN cache servers are also called edge servers or surrogates. The edge servers of a CDN are called Web cluster as a whole. CDNs distribute content to the edge servers in such a way that all of them share the same content and URL. Client requests are redirected to the nearby optimal edge server and it delivers requested content to the end users. Thus, transparency for users is achieved. Additionally, edge servers send accounting information for the delivered content to the accounting system of the CDN for trafﬁc reporting and billing purposes.
CDN contain 4 main component that are:-1. The origin server and a set of replica servers that deliver copies of content to the end users.2. The request-routing component which is responsible for directing client requests to appropriate edge servers and for interacting with the distribution component to keep an up-to-date view of the content stored in the CDN caches.3. Distribution component which moves content from the origin server to the CDN edge servers and ensures consistency of content in the caches.4. The accounting component which maintains logs of client accesses and records the usage of the CDN servers. This information is used for traffic reporting.
A request-routing system is responsible for routing client requests to an appropriate surrogate server for the delivery of content. It consists of a collection of network elements to support request-routing for a single CDN. It directs client requests to the replica server ‘closest’ to the client. However, the closest server may not be thebest surrogate server for servicing the client request. a request-routing system uses a set of metrics such as network proximity, client perceived latency, distance, and replica server load in an attempt to direct users to the closest surrogate that can best serve the request. The content selection and delivery techniques (i.e. Full-site and partial-site) used by a CDN have a direct impact on the design of its request-routing system. If the full-site approach is used by a CDN, the request-routing system assists to direct the client requests to the surrogate servers as they hold all the outsourced content. On the other hand, if the partial-site approach is used, the request-routing system is designed in such a way that on receiving the client request, the origin server delivers the basic content while surrogate servers deliver the embedded objects.
Under the “buy” model, the network operator contracts with the CDN service provider to provide premium multiscreen video services to the network operator’s paying subscribers, and to help deliver online video content more efficiently. To accomplish this, the CDN service provider deploys content caching and streaming assets atvarious points in the network operator’s infrastructure, and takes on the role of adapting the network operator’s licenses content for the broad range of IP devices.Network operators pay a recurring fee for these services, typically calculated based on the volume of traffic delivered on a per-gigabyte basis. Under this model, the CDN operates over the network operator’s edge and access infrastructures, but it functions as an overlay network. The position, form factor, and operation of caching and streaming resources are managed almost entirely by the CDN service provider.Under the CDN “build” model, local caching and streaming resources are once again distributed throughout the network operator’s infrastructure. Unlike the “buy” CDN model, however, the network operator determines the and form factor of all caching and streaming resources, and manages the CDN itself. Under this model, the network operator also has the ability to generate B2B revenue by acting as a CDN service provider itself.CDN “buy” model: At a rate of 6 cents per gigabyte, the network operator pays fees of $32.85 per subscriber per year to the CDN service provider. In total, the network operator pays $1.8 billion in CDN fees over the six-year period.CDN “build” model: At the rate of $5.70 per subscriber described above for CDN hardware, the network operator has a total capital expenditure of $51 million over a six-year period.
Pure-Play :- A company that develops, deploy and operates CDN as its primary business. Example:- Akamai, Limelight and EdgeCast. Pure-play CDN service providers contract with network operators to deploy caching and streaming assets at various points in their infrastructures. CDN service providers therefore have inherent limitations in where and how they deploy CDN assets (typically only in peering or aggregation locations), and therefore, in the ultimate performance and efficiency of the CDN.
Content Delivery Network have played a crucial role in the effective operation of the internet. To mitigate the problem such as congestion, packet loss, jitter and delay
Content Delivery Network
CONTENT DELIVERY NETWORKS Course: Telecom Technologies Prepared By: - Shiv Kumar Pandey MIT School Of Telecom
Content Outline• Overview Content Delivery Network• Content Delivery Network architecture• Content Delivery Management • Content Delivery Network Pricing/Billing • Media Streaming services via CDN’s• Revenue sharing model from CDN• Future Of CDN• Case Study: AKAMAI
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.
Generation of CDN1st Generation :- Focused on Static or Dynamic Web Document2nd Generation :- Focused on Video-on-Demand (VoD), audio and video streaming .
Model of Content Delivery NetworkIt contains 2 parts:-1. Encoded media2. Meta data3 Main entities in CDN systems are:-1. Content Provider2. CDN provider3. End-User
Architectural Component of CDN4 main component:-1. Original server2. Distribution System3. Request Routing System4. Account System
Content Delivery 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:-a) Bandwidth costb) Variation of traffic distributionc) Size of content replicated over surrogate serversd) Number of surrogate servere) Reliability and Stability of the whole system
Pricing Model Of CDN• Pricing Based On Aggregate Usage Charging on Monthly basis that is 50TB/month• Percentile – Based PricingPricing based on the 95th percentile of traffic CDN periodicallysamples the bandwidth usage of a subscribing content provider. It thencomputes the 95th percentile of usage at the end of the month andcharges a price per Mbps based on the 95th percentile of usage.
Model of Revenue Sharing “BUY” MODEL “BUILD” MODELNetwork operator pays $1.8 billion in CDN fees over the Network operator has a total capital expenditure of $51six-year period. million over a six-year period.
Content Provider And Aggregator• Netflix ,BBC and other rely on “pure-play”• Network operator globally providing services are Telco, Cable operator such as Rogers cable, Comcast, Telecom Italia
Future OF Content Delivery Network Global Content Delivery Network revenueVideo:- $3.8 billion US
INDIA3 Network Operators :-• Aksh Optifibre Ltd.• IOL Netcom (formerly IOL Broadband Ltd. )• Time Broadband Services GroupThese 3 company have invested in CDN to provide managed video andIPTV services to India’s operators
Akamai Technologies• 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.
CDN Service and Functionalities• 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