CDN network architecture
04 Aug 2015

CDN Network Architecture

Content Delivery Network (CDN) is the main artery, through which users from all over the world receive the media content and other information. Actually, Content Distribution Networkchanged the way how large files delivering to end users. These changes can be called revolutionary. This has been made possible due to CDN network architecture.

CDN have to deliver file access and caching features to end users. That is why it should contain such elements as request, distribution and delivery. The first element deals with an ability of systems and users to ask (request) for a specific content (data, media content). Special protocols (such as WCCP) intercept and redirect every request from the end user to the closest CDN engines. When user’s request has been made, Content Delivery Network engines can decide, what they can do with it. If they can, they will answer on it. If not – they will proxy the request on the user’s behalf. The next element, distribution, is very close to a request element. Distribution element decides which action will be appropriate for user’s request – to answer or proxy. One or another way, requested content should come from the CDN origin server. Every content element is based on requests and patterns of use. However, Content Delivery Network administrators can distribute it appropriately. In turn, the choice of distribution affects the details of a request. The last CDN element, delivery, is responsible of getting content to proper locations within architecture. To make delivery reliable and efficient, Content Distribution Networkcompany needs to be sure in the switching and routing infrastructure.

Every Content Distribution Networkis composed from replicated web servers clusters. Such Pops (Points of Presence) are usually located to make them geographically close to end users. Different CDN companies have different amount of Pops. For example, CDNsun has 85 POps all over the world – 25 in America, 44 in and 16 in Asia Pacific. For CloudFront, CacheFly  and MaxCDN it will be 52, 41 and 16 Pops all over the world. More points of presence for Content Distribution Network company gives more benefits to their customers. This conclusion is very simple, but shows the idea of CDN architecture. Content Distribution Network pulls the data from the origin server and caching it onto its network. Each customer decides which data to share through the Content Delivery Network. After that the identical copy of this data will be placed on delivery servers. Due to this there are several benefits of CDN online: better response and latency time, faster download speeds, file integrity and bigger independence from servers. Better response and latency time is possible because of geographically close distribution of Pops. Such shorter distance from server to the end user reduces the likelihood of errors. For the same reason file’s integrity is in a greater safety. Shorter distance influences on a download speed too. When download locations (Pops) are multiple, servers are less like to become overloaded. Again, even if some of multiple servers are overloaded, requested data will be still loading from others. Another benefit, which Content Distribution Networkarchitecture gives, is bigger safety for data – each server gives a life backup for it.

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