Content Delivery Network

A content delivery network is sometimes called a content distribution network. It is a computer system that contains data copies distributed over different network nodes. If a CDN is properly implemented and designed, it can improve data access by reducing latency and increasing bandwidth and redundancy.

You should be using a Content Delivery Network because it delivers your content a lightning fast speed as no-one wants to wait for a slow-loading website.

Content Delivery Networks Offer

  • Improved Google Rankings
  • Increased Page views
  • Lower Bounce Rates
  • Improved Conversion Rates

Best of all a content delivery network ensures your visitor enjoys the browse-to-purchase experience and their entire session is smooth, reliable and super fast.

How Content Delivery Networks Help You

  • The data is sent to your visitor by the shortest route
  • There is no annoying pauses when they are streaming content
  • There is no site down time as no single server is responsible
  • You can respond to temporary burst requests easily
  • Prepare for traffic surges without a moment’s hesitation

Leading Content Delivery Networks

CDN benefits
There are many benefits of a Content Delivery Network.

  • The capacity of a CDN can well exceed that of the network backbone capacity which can increase the concurrent users
  • If an edge server is strategically placed, it can decrease the interconnectivity loads, public and private peer loads and backbones. This frees up the capacity as well as lowers the delivery cost.
  • A CDN delivers content over UDP and TCP connections. In order to reduce the latency and packet loss, a CDN server is placed close to the edge networks that are used by the users. In theory and practice, fast delivery is possible if the content is close. With such placing, a user may experience less jitter, increased reliability, improved streaming quality and few network surges and peaks
  • A CDN has the capability to distribute dynamically the assets to redundant core and edge network servers. A CDN is available anytime even if there is a large power or network outage.
  • CDN technologies allow the user to have more control over the delivery of asset and network load. These technologies can optimize performance by increasing capacity per customer; provide real-time statistics and load views and usage details and so on.

Content Delivery Network Technology
A CDN node is installed in different locations over different backbones. There can be more than one node which coordinate with each other to meet the content request made by a user. The content is then moved over these nodes to optimize the process of delivery. The optimized delivery process can reduce bandwidth costs, improve user performance and increase the availability of content globally.
A CDN can be made up of various numbers of servers and nodes depending on the required architecture. Some CDN architectures have hundreds of nodes with hundreds of servers on different remote PoPs. Requests are forwarded to the nodes using algorithms to optimize the performance.
In addition, locations play an important part in optimization. Locations that are few hops and few network seconds away from the user will have a better delivery performance.

CDN Networking techniques
A content delivery network is designed to supplement the end-to-end data transport by distributing it on different intelligent applications. These applications use techniques that can optimize the content to be delivered. For this purpose, closely integrated overlay are used for web caching, request routing, server-load balancing and content services.
In web caching technique, a CDN server stores regularly accessed information that help in reducing bandwidth and server load to improve the response time. Server load balancing is a technique that includes service and hardware based balancing including web switch, multilayer switch and content switch. Using a ‘4 – 7 switch’, a service node or a content cluster can be created to switch the load balance over different servers.

CDN Service providers
The list of CDN service providers is a long one as it is categorized in four parts:
Free CDN providers

  • MediaBlog
  • PeerCast
  • PPLive
  • Coral CDN
  • PPStream
  • CoBlitz

Commercial CDN Providers

  • Akamai Technologies
  • AT&T
  • CDNetworks
  • Internap
  • LimeLight Networks
  • Windows Azure CDN
  • Cotendo

Telecommunication CDN providers

  • AT&T
  • BT Group Bell Canada
  • KPN
  • Orange
  • SingTel
  • Reliance Globalcom
  • Tata Communications
  • Verizon

Commercial P2P CDN Providers

  • Internap
  • Pando Networks
  • Bit Torrent Inc
  • Octoshape

Commercial vs. Free Content Delivery Networks
Commercial CDN  – CDNs sold commercially offer a high quality user experience. This is because when a customer purchases a CDN system, he/she expects that the company will provide high-quality services such as high bandwidth, low latency and high security services. In addition, commercial CDN spreads the content of static websites over different locations and servers for optimal performance.
Free CDN – Many companies offer free CDN services using P2P technology. P2P can lower the strain on a server only if high quality media files are possessed, and in addition, free CDNs do not spread the static web content across different locations. Therefore the quality of service is not equal to that provided by commercial companies.

Pricing of Content Delivery Networks
Commercial CDN providers charge for the service based on the web traffic. Pricing of a CDN service is a complex process. Each company has its own pricing policy based on different elements. A few common factors on which the price of a CDN is established are:

  • Traffic variation and distribution
  • Number of surrogate servers
  • Cost of bandwidth
  • Size of content to be replicated
  • Stability and reliability of a CDN system
  • Security concerns

Types of CDN services
A CDN can provide a range of services such as simple caching services to full remote delivery of application. In addition, a CDN deploys different content delivery methods such as manual asset copying, global hardware load-balancing and web caches.
As a web cache, frequently accessed data is stored on a CDN which can be retrieved quickly as the bandwidth is reduced, dedicated server is not overloaded and response-time is lower.
Another service that a CDN can provide is of a load-balancer. When the server content is being distributed and duplicated from different locations, a CDN reduce or manage the load.
A CDN can also act as an application service provider. It provides software including SaaS which is similar to cloud computing.

Types of content delivered
A CDN is mostly effectively used to deliver rich media content such as streaming, caching and progressive downloading. Streaming is best delivered if CDN is used. This provides decreased latency, reduced buffering and no waiting for download times.
Downloading speed is also increased as a CDN can balance and download the delivery route to the end user such as new software downloads, game downloads, audio, HD video and so on.
A CDN is an optimal solution for caching content that although static is occasionally accessed such as online shopping, social networking sites, travel sites and hosting sites.
Content Delivery Networks vs. traditional ISP
Advantages that were once restricted to ISPs have now shifted to P2P CDNs. ISPs that once acted as peers have become indirect distribution servers that generate no revenue from content delivery. This is because a CDN system does not require any big investment in infrastructure; it is self-scalable; the system is resilient to demand hikes as it can adjust automatically to demand; and it can provide the best performance as it capitalizes on the end –nodes’ bandwidth.