video & live streaming

What Is CDN (Content Delivery Network) And How Does It Work?

What is CDN (Content Delivery Network)?

CDN (Content Delivery Network) can be defined as a strategically distributed and geographically dispersed platform of servers and their data centers optimized to work in order to deliver Internet content swiftly and efficiently upon the requests of the end-users. Internet Content may include:

-Web items like graphics, text.
-Downloadable items like documents, media files, software.
-Social media sites like YouTube, Facebook, WeChat, to name a few.
-Live streaming media or Live Video Streaming
-On-demand streaming media
-Applications such as e-commerce
CDN services are very popular and always growing as a large part of web traffic is served through CDNs today especially Video CDN.

How does a CDN (Content Delivery Network) work?

We have previously understood that a CDN is basically a large network of various servers located in several geographic zones. In order to lessen the distance between the visitors and a server, let’s say any website’s, what a CDN does is, it reserves a cached version of the content in multiple locations, PoPs (Point of Presence). Each PoP has a good quantity of caching servers accountable for content delivery to visitors within its vicinity.

When a visitor requests for static content from a particular location (e.g. London), that static content will be retrieved from the original server. Upon being delivered, the content will be cached on the London edge server (or the nearest POP to the visitor). If the visitor requests for the same content again, the request will be directed to CDN PoP edge server to check if the content has been already cached.  If yes, the visitor gets a response from that server. And, if not, it will be cached again from the origin server.

CDN hosting operates with CDN management server.  In response to a web query, the nearest server is provided to the user. The content traveling distance is reduced, thereby speeding up the delivery of the content.

CDN (Content Delivery Network)
Diagram: CDN (Content Delivery Network)

CDN providers aid in the secure delivery of the requested contents. PoPs are networks of servers located globally. In case of live video streaming, broadcasting and video on demand cases in a CDN network, media transcoding is vital.

Benefits of CDNs:

  • Speed: The closer a user’s network, the better the speed and lower the latency.
  • Concurrent users: Many users can access the network simultaneously without any delay as a CDN allows a network to possess high data threshold by sanctioning a higher flow of traffic.
  • Redundancy: Other nodes take up charges in traffic handling when one node proves to be unsuccessful.
  • Load Balancing: Since content is outspread through various servers instead of offloading on a single large server.
  • Minimal Packet Loss: Nominal hops results in a reduction in packet loss, which is why the users achieve revamped quality in streaming.
  • Security: CDN node levels consist of several extra layers of protection. Most CDN Providers, if not all, do so and have DDoS attack protection mitigations.
  • Lower costs: Bandwidth cost is minimum in contrary to all the traffic being served from a center.
  • Accommodate Heavy Traffic: CDN providers aid in delivering better user experiences to download video and audio by absorbing traffic with their highly distributed architecture and massive server platforms.
  • Eliminate Pauses: CDNs ensure the jitters and pauses during video streaming due to lags in transmission period are alleviated.
  • Easier segmentation of audience: CDN providers cater to different contents to different users depending on the type of device requesting the content.
  • SEO benefits: Websites using CDN are rewarded with higher rankings on search results by search engines.

Who can use a CDN?

The answer is everyone.

It is no surprise that CDNs are already serving nearly over half of all internet traffic. But truth be told, although many CDNs today offer their services free of charge, CDNs aren’t literally for everyone. If most of the users are located in the same area as the hosting, having a CDN will mean negligible benefits. In this case, a CDN may even worsen the website’s performance by establishing an unnecessary connection between the visitor and a nearby server.

Nevertheless, CDN usage is popular in sectors like Government, higher education, healthcare, advertising, media and entertainment, online gaming, E-commerce, live video streaming, mobile, etc.

CDN market demand/why it is so important

CDN (Content Delivery Network) market demand is increasing day by day because of the increased demand for rich video content. Therefore, video CDNs are of the highest demand.  It was valued $7.33 billion in 2017 and predicted to reach $29.48 billion within 2023. Rising online users (nearly 10 times compared with the last decade) is one of the main causes of this market’s growth. Due to technological evolution, 4k/8k UHD television, HD supporting smart gadget and improved connectivity are available now. This technological advancement has been rising the expectation among end users for high-quality content. Furthermore, many gaming services adopting online channels now, and perform live video streaming using Youtube Live, which also enables market growth.

Popular CDN (Content Delivery Networks):

Popular commercial CDN (content delivery networks) include the following companies:

  • Akamai
  • Amazon CloudFront
  • CloudFlare (free)
  • Google Cloud CDN
  • KeyCDN
  • MaxCDN
  • Microsoft Azure CDN
  • Incapsula (free)
  • Photon by Jetpack
  • Swarmify
  • AWS Cloudfront
  • Cloudinary

Top 5 ideal CDNs for Video Streaming:

  • MaxCDN
  • Cachefly
  • CloudFlare
  • Edgecast
  • Incapsula

Streaming solution providers vs. CDN providers

We have already discussed how one of the two distinct kinds of video delivery services works, that is CDN providers.
As for the second type of video delivery service, known as OVPs (Online Video Platforms), it can be referred to as a service focused primarily on hosting video streaming as well as often live streaming. Although these platforms are smaller than CDNs, but they ensure the delivery with exceptional functionality and a reasonable pricing. There are OVPs that partner with CDN providers and they undoubtedly yield the best performance. Some online video platforms are:

  • Wowza
  • DaCast
  • UStream
  • LiveStream
  • YouTube Live
  • FaceBook Live
  • Periscope
  • Twitch Live

In keeping a site running quickly and smoothly, CDN (Content Delivery Network) has an indispensable role. Using CDNs means an increase in performance, thus giving the end users an enhanced experience. Therefore, today, many of the world’s top companies and organizations do business successfully online by heavily relying on this technology. And the worldwide market for content delivery network services is on the rise steadily.