Advanced Content Delivery, Streaming, and Cloud Services

Chapter 5Anycast Request Routing for Content Delivery Networks

Hussein A. Alzoubi¹, Michael Rabinovich¹, Seungjoon Lee², Kobus Van Der Merwe³, and Oliver Spatscheck²

¹Case Western Reserve University, Cleveland, OH, USA

²AT&T Labs—Research, Florham Park, NJ, USA

³University of Utah, Salt Lake City, UT, USA

5.1 Introduction

As the Internet continues to grow, the need to distribute digital content to end-users in a timely and efficient manner became a priority for most Web content providers. Accomplishing this goal is challenging because of the often bursty nature of demand for such content [1] and also because content owners require their content to be highly available and be delivered in timely manner without impacting presentation quality [2]. Content delivery networks (CDNs) (e.g., Akamai, Limelight) have emerged over the last decade as an answer to this challenge and have become an essential part of the current Internet apparatus. In fact, Akamai alone claims to deliver between 15% and 30% of all Web traffic [3].

The basic architecture of most CDNs consists of a set of CDN nodes distributed across the Internet [4]. These CDN nodes serve as content servers' surrogates from which clients retrieve content from the CDN nodes using a number of standard protocols. The key to the effective operation of any CDN is to direct users to the “best” CDN node, a process normally referred to as “redirection” or “request routing” [5]. Redirection is challenging because not all content is ...