CDN


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CDN

(Content Delivery Network) A distribution system on the Internet that accelerates the delivery of Web pages, audio, video and other Internet-based content to users around the world. The CDN replicates the content provider's files in servers, called "caching servers" or "edge servers," located in geographically dispersed datacenters. Most CDNs are third-party services; however, large companies may develop their own "enterprise CDN" (eCDN) to support remote locations more effectively.

When content is replicated throughout the country or the world, it is delivered to users with greater speed and reliability. The CDN network routes the user's request for content to the appropriate caching server based on the user's location. CDNs are often connected to multiple ISP backbones and have peering relationships with others, providing high availability to users.

Types of Services



Web Acceleration
Every CDN accelerates content delivery by nature of its multiple backbones (in most cases) and numerous caching servers. A CDN may also augment acceleration via compression between nodes in its own network. Quite often, only the graphics on a Web page are delivered by the CDN, while the HTML text is sent out from the customer's servers.

Streaming and Downloading
Video uses extensive network bandwidth, and many customers of a CDN use the service solely to stream video to Web users. A CDN may offer all popular streaming methods such as Flash, Windows Media, Silverlight and progressive download, the latter using the same HTTP protocol as Web pages (see progressive download). Large downloads such as gaming software are also candidates for CDNs. The CDN may pull the data from the customer's origin server, or the customer may upload the files to the CDN.

Server-Side Processing
The CDN may offer server-side processing of Java and ASP scripts. If the CDN does not provide server-side processing, that operation takes place in the customer's servers, and the CDN can deliver the accompanying graphics or other downloads.

Hybrid CDN (Peer-to-Peer)
A CDN may support peer-to-peer processing, which requires client software to be installed in the user's computer or pre-installed in a set-top box.

The Vendors
Akamai Technologies (www.akamai.com), one of the first CDNs and by far the leader, delivers content for some of the largest content publishers in the world. As of 2008, Akamai, along with Limelight Networks (www.llnw.com) and CDNetworks (www.cdnetworks.com), had the lion's share of CDN revenues. Limelight keeps much of its customer traffic on its own international fiber network, and CDNetworks has extensive penetration in the Asian market.

Founded by DoubleClick executives in 2005, Panther Express, which later merged with CDNetworks, offered a progressive download service to content publishers of all sizes. Panther made it easy for small websites to come on board and expand. See content peering and Akamai.


Akamai's Control Center
Moving massive amounts of content every minute of the day, perhaps no other company in the world has a handle on the current state of the Internet as does Akamai. In mid-2008, its rotating world display (bottom) showed more than a trillion bits per second of content being transmitted at that moment.


Akamai's Control Center
Moving massive amounts of content every minute of the day, perhaps no other company in the world has a handle on the current state of the Internet as does Akamai. In mid-2008, its rotating world display (bottom) showed more than a trillion bits per second of content being transmitted at that moment.
References in periodicals archive ?
What it soon finds is a DNS server maintained by the CDN which does a little more than the usual DNS operation: it figures out where the local DNS server, originally queried by the browser, is geographically and returns the address of one of the CDN's network of cache servers that is closest to that DNS server and thus likely closest to the browser.
OnApp CDN was announced in August 2011 and launched at the beginning of 2012.
Pacnet's CDN takes advantage of new reseller and routing functionality within the OnApp CDN platform.
The market is worth an estimated $600 million in 2006, including direct bandwidth accounts that do not go through a CDN specialist for distribution (i.
CDN Technologies, a key reseller of SAVVIS Content Delivery Services in France, support, market and sell SAVVIS services in order to offer their customers the strongest alternative in a quasi monopolistic market.
The break out of streaming traffic delivered by format (as reported by the CDN specialists) includes Windows Media at 58.
Highwinds Licensed CDN enables customers to add CDN services to their solutions portfolio and grow in a way that both leverages their own network strengths and subsidizes their network expansion.
The warrant will terminate within 20 days unless exercised in the event the Company's closing stock price meets or exceeds CDN $2.
It is intended to provide buyers of media delivery services with guidance on industry pricing, best practices, and engagement methodologies that can be used to balance CDN costs with required service levels.
AdMedian identified SAVVIS' CDN as the best qualified to support AdMedian's rapidly growing online advertising and soon to be launched publisher business.
Through this alliance program and agreement, CDN agrees to promote @Road solutions, such as the @Road Transportation and Distribution Suite, to each of its members.