Content Delivery Network companies replicate content caches close to a large user population. They don’t provide Internet access or transit service to the customers or ISPs but distribute the content of the content providers. Today, many Internet Service Providers started their own CDN businesses as well. An example is Level 3. Level 3 provides its CDN services from its POP locations which are spread all over the World.Content distribution networks reduce latency and increase service resilience (Content is replicated to more than one location). More popular contents are cached locally and the least popular ones can be served from the origin
Why CDN - Content Delivery Networks are necessary?
Before CDNs, the contents were served from the source locations which increased latency, thus reducing throughput. Contents were delivered from the central site. User requests were reaching the central site where the source was located.
Figure 1 - Before CDN
With CDN Technology, the Contents are distributed to the local sites.
Figure 2 - After CDN
Amazon, Akamai, Limelight, Fastly, and Cloudflare are the largest CDN providers which provide services to different content providers all over the world. Also, some major content providers such as Google, Facebook, Netflix, etc. prefer to build their own CDN infrastructures and become large CDN providers.
CDN providers have servers all around the world. These servers are located Inside the Service Provider networks and the Internet Exchange Points. They have thousands of servers and they serve a huge amount of Internet content. CDNs are highly distributed platforms. As mentioned before, Akamai is one of the Content Delivery Networks.
The number of servers, number of countries, daily transactions, and more information about Akamai’s Content Distribution Network are as follows:
- 150.000 servers
- Located in 92 countries around the world
- Delivers over 2 trillion Internet interactions daily
- Delivers approximately 30% of all Web traffic
- Their customers include: All top 20 global eCommerce sites, top 30 media companies, 7 of the top 10 banks, 9 of the largest newspapers, 9 out of 10 top social media sites