This content delivery network (CDN) primer gives you a brief overview of the technology and why it matters to enterprises, especially IT managers in the wide area networking (WAN) space. Understand the purpose and advantages of CDNs, and get a brief introduction to the market of CDN providers.
What are content delivery networks?
A content delivery network (CDN) is a system of servers, or computers interconnected over the Internet, that are placed closer to users across the globe to reduce the distance content travels across long-haul networks, like wide are networks (WANs). These servers contain duplicate content of the originating network. CDNs dynamically provide data to clients by calculating which server is located nearest to the client and delivering content based on those calculations. This not only eliminates the distance that content travels, but reduces the number of hops a data packet must make. The result is less packet loss, optimized bandwidth and faster performance -- improving overall user experience.
Why you need to know about content delivery networks
No matter how you look at it, transporting content over a wide area network (WAN) will take longer than transporting content over a local area network (LAN) -- based purely on distance. This makes real-time communication data such as streaming video/audio and Internet television (IPTV) especially difficult to deliver because of its high bandwidth and susceptibility to latency -- causing jitter. CDNs are ideal for eliminating this type of latency since they provide content housed closer to the user.
A CDN is also ideal for Web content (static or otherwise) experiencing a surge in traffic because distributed CDN servers can handle a sudden large number of client requests at one time over the Internet. For example, spikes in Internet traffic from flash crowds due to a popular event, such as an online streaming video of a presidential inauguration, can be spread out across the CDN, making content delivery faster and less likely to fail.
What you need to know about content delivery networks and CDN providers
Rather than incur the expense of creating in-house CDNs, most enterprises use an Internet service provider (ISP) or specialized CDN provider. CDN customers find they can improve site performance and pay less for data transfer because CDN providers offer pay-as-you-go services at considerably lower costs. Anyone looking to improve WAN performance or content delivery can use a CDN provider.
According to a Current Analysis content delivery networks market assessment, CDN providers have a range of offerings including products, services and tools that ameliorate Web content -- ranging from streaming media, static and dynamic content transport and applications.
Depending on your current network requirements, size, growth rate and the content you are aiming to optimize, you will need to examine individual content delivery network services along with their offerings. The largest CDN provider at the top of the market is Akamai Technologies. Other providers in the commercial CDN market include Amazon CloudFront, AT&T's Digital Media Solutions, BitTorrent Inc., BitGravity, CDNetworks, Edgecast, GoGrid, Limelight Networks, and PEER 1, to name only a few. Some CDN providers are free (like PeerCast), but more enterprise-class CDN providers offer initial account costs of $500 and go into the thousands of dollars with larger business accounts.
This was first published in February 2010