EVOLUTION OF CDN

Content delivery networks were actually functioning quietly in the background for a quite

long time. It was required since the emergence of Internet to ease the way web content could

Publishes & Stores Content

Publisher

Content Origin

Content Delivery Network

Transfer of published content

Authorizes

Subscriber

Subscriber

Content Request

Content Request

Content Delivery

Content Delivery

FIG 15.1: The model of Content Delivery Network263

Content Delivery Network

be delivered to consumers. CDN first emerged towards the end of the last century to enable

websites to keep pace with growing Internet usage.

During that period, the CDN was being developed in United States to support growing

demand of newspaper like the New York Times for faster delivery of graphics via caches. Players

like Limelight and Akamai in particular led the development. That time it was commonly

referred as web acceleration which used to hoard frequently-requested content in servers closer

to the points of consumption.

In the very early days of Internet, web-content was almost entirely static. Hence the service

providers (ISP) used to segregate the parts of web pages which would rarely change and cached

them out in servers. With the increase in dynamic content, the service providers started

pushing the updated dynamic parts of pages on to the caches in real-time scenario.

In the early years of the current century, with the rapid increase in storage capacity and

network band-width, web sites started embedding video files. This abruptly increased the

amount of data CDNs had to handle. But, then the video content which were being embedded

to websites were all pre-recorded and hence were static. Delivery of such videos was not very

difficult as these were only large files to be delivered over the network.

But, with time the demand for live video streaming started increasing and this paved the

way for second generation of CDN. This time the focus shifted from static video content to

dynamic (live) videos. The focus of the new CDN system was on video-on-demand (VoD),

audio and video streaming with interactivity amongst the users. Additionally, the second

generation CDN focussed on cloud computing and content delivery for mobile users.

CDN operators, Akami and Limelight, led the development of the technology in initial years

 
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