Challenges and opportunities in content distribution networks: A case study

In this paper we present some contemporary examples of research-oriented as well as commercial content delivery networks (CDN)s. We discuss how both types of CDNs complement each other in tackling the posed technical and commercial challenges. We also show which performance metrics such as quality of experience (QoE) and time to first byte (TTFB) best capture the dynamics of traffic and services in CDNs. The core of this paper is our proposed network architecture for CDN providers/operators. The architecture combines video multicast optimized trees and cross-layer coordination between the physical DWDM layer (L1) and network layer (L3) for achieving higher efficiency and lower latency values for live streaming and on demand (VoD) video. Due to the pilot implementation of the presented concept being limited in scale, we use simulations in order to perform proof-of-concept on a sufficiently large environment. Results show that there is a strong correlation between the TTFB and QoE metrics with the former taking on values as low as 75 msec in a national 3-tier network.