Performance Caching: Content Delivery Networks

January 8, 2008

As online business owners and IT professionals, we like to stay on top of things — it gives us a reason to get up in the morning. Something we always want to know is how we can improve the Internet experience for our customers, and make our own jobs easier at the same time. The solution is simpler than it may first appear — a Content Delivery Network, or CDN, is a highly efficient and cost-effective aid in the distribution of digital content over the Web.

In a typical Web server environment, all requests from users are sent to the same server, known as the origin server. The origin server processes all user requests and distributes content accordingly. This works out fine for most Web sites; however, when large quantities of content such as music, video, applications, and other downloads are being served each day, the load can potentially overwhelm and bring down a single server. This will often result in the need for more powerful server equipment and increased bandwidth to support the growing need, which can be very costly and time-consuming to implement and maintain. Using a Content Delivery Network with content caching technology, performance of your Web site is dramatically improved for all users with no extra hardware to implement, and the network backbone is already in place, making the overall network implementation time very small.

Content caching is the technology that drives the CDN. Essentially, a CDN is a network of servers that are strategically placed in such a way that there is at least one caching server, known as a CDN node, in every region of the world. This way, there is a CDN node close to each individual end user. Under the CDN model, when a user visits your Web site and requests content, that request actually goes to the nearest CDN node. The node then checks to see if it has the content requested; if it does not, a request will be made back to the origin server to retrieve the content. A copy of this content is now cached on that node, so that when users in the same region request the same content, that content is served by the CDN node rather than the origin server. This splits up the load between all nodes on the CDN, so the only requests made to the origin server come from the CDN nodes themselves, greatly increasing site performance while taking major pressure off the origin server. The distance factor plays a part as well; the CDN node is much closer to the user than the origin server, so content loads much quicker due to the reduced distance that data must travel to reach the end user. In addition, because the CDN uses its own backbone, it is not susceptible to Internet congestion, and the reduced pressure on the origin server decreases the need to spend money on additional server hardware.

The advantages of a CDN are not limited to customer satisfaction and server performance – there are a host of other benefits as well.

An ever-pressing issue concerning online businesses is that of sudden surges in traffic, known as flash crowds. Flash crowds can be anticipated, such as in the event of a big sale or product launch, or they can be unanticipated, whether appearing randomly or as a result of unexpected media attention, such as a story on the news. Flash crowds can be difficult and costly to plan for, due to the need of installing more robust server hardware to handle the excess traffic. This extra hardware often goes unused because flash crowds may not occur frequently. Using a Content Delivery Network, however, the extra traffic is offloaded to the CDN nodes caching your site’s content, so the origin server is at little or no risk of being overloaded and there is no need to buy extra hardware. This load-balancing technology not only increases site efficiency, but also extends the life of your server hardware.

Security can be a very potent feature of a Content Delivery Network. The origin server holds information that is vital to the operation of your business, and that content must be protected from Web attacks. Using a CDN, the origin server can be “hidden” from the Internet by a group of CDN nodes, and only the IP addresses of those particular nodes will be able to access the origin server. All requests for content from the origin server will be sent to those nodes guarding it; those nodes will then request the content from the origin server and send it back to the original requesting node.

Another benefit of a CDN is global availability of content. In the United States, Internet infrastructure is everywhere; bandwidth capabilities are virtually limitless. Transferring content over the Internet using a CDN in the United States can increase Web site performance by up to a hundred percent. In Asia and other parts of the world, such capabilities are far more limited due to a lack of public infrastructure; using a global CDN, however, these limits are essentially removed. Content can be delivered all around the world using caching servers and the CDN backbone, allowing countries outside the United States to view content with a level of performance that would not be possible without the aid of a CDN. This allows online businesses to effectively and efficiently serve customers worldwide.

Performance, availability, and security are the primary functions of a Content Delivery Network, but its benefits stem far beyond those. The network is already in place, so implementation time is low, and no extra server hardware is needed; at the same time, your Web site’s performance is greatly increased, and content is made more readily available. A CDN gives online businesses an avenue to deliver content quickly and efficiently to all corners of the globe, making it an ideal solution for any content-driven business.

Brian Lowy is a CDN Account Executive for EC Suite; a leading provider of Content Delivery Networks (CDN), wholesale IP Transit, IP Transport, website hosting, and content protection. Learn more about Content Delivery Networks at