System Design: The Content Delivery Network (CDN)

Problem statement

Let’s start with a question: If millions of users worldwide use our data-intensive applications, and our service is deployed in a single data center to serve the users’ requests, what possible problems can arise?

The following problems can arise:

• High latency: The user-perceived latency will be high due to the physical distance from the serving data center. User-perceived latency has many components, such as transmission delays (a function of available bandwidth), propagation delays (a function of distance), queuing delays (a function of network congestion), and nodal processing delays. Therefore, data transmission over a large distance results in higher latency. Real-time applications require a latency below 200 milliseconds (ms) in general. For the Voice over Internet Protocol (VoIP), latency should not be more than 150 ms, whereas video streaming applications cannot tolerate a latency above a few seconds.

Note: According to one of the readings taken on December 21, 2021, the ...