Content Delivery Network

From Free net encyclopedia

Content Delivery Network (CDN), also called Enterprise Content Delivery Network, (ECDN), is a term coined in the late 1990's to describe a system of computers networked together across the Internet that cooperate transparently to deliver content (especially large media content) to end users.

CDN nodes are deployed in multiple locations, often over multiple backbones. These nodes cooperate with each other to satisfy requests for content by end users, transparently moving content behind the scenes to optimize the delivery process. Optimization can take the form of reducing bandwidth costs, improving end-user performance, or both.

The number of nodes and servers making up a CDN varies, depending on the architecture, some reaching thousands of nodes with tens of thousands of servers.

Requests for content are intelligently directed to nodes that are optimal in some way. When optimizing for performance, locations that can serve content quickly to the user may be chosen. This may be measured by choosing locations that are the fewest hops or fewest number of network seconds away from the requestor, so as to optimize delivery across local networks. When optimizing for cost, locations that are less expensive to serve from may be chosen instead. Often these two goals tend to align, as servers that are close to the end user sometimes have an advantage in serving costs, perhaps because they are located within the same network as the end user.

1 Commercial history
2 Commercial CDNs
3 Academic CDNs
4 External links

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Commercial history

NEXUS International Broadcasting Association based in Milan, Italy, developed the first known CDN in 1995. This non profit organization acted as a research incubator with hi-tech professionals in the computing, telephone and media industries for a number of media related technologies. Since early 1995 NEXUS-IBA's CDN technology - called WorldDirector - has been used for distribution of NEXUS-IBA members' audio streaming channels, as well as ftp archives and web pages belonging to the Association's members. WorldDirector CDN is now available through Wornex International at [1].

iBEAM Broadcasting, InterVU, NextVenu and Sandpiper Networks were other early pioneers in CDN's. Akamai Technologies is more well known. InterVU was purchased by Akamai in April 2000. Sandpiper was purchased by Digital Island who was subsequently purchased by Cable & Wireless and is now owned by Savvis. iBEAM purchased NextVenu in June of 2001.

iBEAM was the first streaming media CDN and was the first to efficiently use satellites for content replication. Additionally iBEAM invented the on-net delivery business model where content would be delivered to consumers on their local networks and not across costly Internet exchange points. In 2001, iBEAM was a clear leader with over 1,000 accounts and over 1 billion streams served. Microsoft estimated that iBEAM was responsible for over 80% of all hosted streaming media on the Internet. iBEAM had an IPO in early 2000 and at its peak was valued at over 2 billion dollars. Just before the IPO Akamai offered to purchase iBEAM for 4 billion dollars, a deal that was refused at the time. Due to bad business management during the pre-bubbble-burst market, iBEAM signed bloated long term contracts which could not be honored after the bubble burst in late 2001. iBEAM sold to Williams Communications in the summer of 2001. iBEAM has 8 patents pending which are now owned by Williams Communications, Inc.

Some more recent entries into the space are Mirror Image, Lime Light and Panther Express.

U.S. Patent and Trademark Office issued U.S. Patent No. 6,108,703, "Global Hosting System,". The patent was granted to MIT in the names of Tom Leighton, Akamai's chief scientist, and Danny Lewin, Akamai's chief technology officer.

Digital Island, via its acquisition of Sandpiper Networks, was issued U.S. Patent No. 6,185,598, " Optimized network resource location", which was based on the work of chief system strategist David Farber and vice president Andrew Swart.

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