System Design: The Content Delivery Network (CDN)
Define the critical performance and scaling problems of serving global users from a single data center. Analyze how high latency and resource strain necessitate a distributed solution. Justify the fundamental need for a content delivery network (CDN) in modern System Design.
Problem statement
Consider a data-intensive application serving millions of global users from a single data center. This centralized architecture faces several critical challenges:
High latency: Physical distance between clients and servers increases user-perceived latency. Total latency consists of transmission delay (limited by bandwidth), propagation delay (signal travel time), queuing delay (network congestion), and processing delay. Real-time applications such as VoIP typically require end-to-end latency below 150 ms, while video streaming can tolerate higher delays but degrades with multi-second latency.
Note: According to readings from December 2021, the average round-trip latency from US East (N. Virginia) to US West (N. California) ...