A taxonomy of CDNs

Abstract

In this chapter, we have analyzed and categorized CDNs according to the functional and non-functional attributes. We have developed a comprehensive taxonomy for CDNs based on four issues: CDN composition, content distribution and management, request-routing, and performance measurement. We further built up taxonomies for each of these paradigms to classify the common trends, solutions, and techniques in content networking. Additionally, we identify three issues, namely, fault tolerance, security, and ability for Web application hosting as to introduce challenges in CDN development. Hereby, we provided pointers to related research work in this context. Our taxonomy provides a basis for comparison of existing CDNs. In doing so, we assist the readers to gain insights into the technology, services, strategies, and practices that are currently followed in this field. We have also performed a mapping of the taxonomy to representative commercial and academic CDN systems. Such a mapping provides a basis to realize an in-depth understanding of the state-of-the-art technologies in content distribution space, and to validate the applicability and accuracy of the taxonomy. Recently, the CDN industry is getting consolidated as a result of acquisitions and/or mergers. During the preparation of this chapter, we have experienced significant changes in the content distribution landscape due to this consolidation. Consequently, content distribution, caching, and replication techniques are gaining more attention in order to meet up the new technical and infrastructure requirements for the next generation CDNs. This may lead to new issues in the design, architecture, and development of CDNs. Present trends in content networking domain indicate that better understanding and interpretation of the essential concepts in this area is necessary. Therefore, we hope that the comprehensive comparison framework based on our taxonomy, presented in this chapter, will not only serve as a tool to understand this complex area, but also will help to map the future research efforts in content networking. © Springer-Verlag Berlin Heidelberg 2008.