Energy efficiency of cache collaboration in core content distribution networks

Article type: Research Article

Authors: Osman, Niemah Izzeldin^{; *}

Affiliations: Department of Computer Systems and Networks, Sudan University of Science and Technology, P.O. Box 407, Khartoum, Sudan

Correspondence: [*] Corresponding author. E-mail: niema.osman@gmail.com.

Abstract: With escalating demands for high-definition video, cache collaboration allows neighbor nodes to share locally stored content in order to reduce download traffic. High energy consumption associated with content delivery remains a concern for Content Distribution Networks (CDNs). Therefore, this paper proposes cluster-based collaborative caching in a core network employing IP over WDM. The aim is to allow sets of core caches to fully share content while minimizing power. A Mixed Integer Linear Programming (MILP) model is used to form energy-efficient cache clusters. The energy consumption of the network is evaluated under different cluster sizes to find the optimum size that minimizes energy. To evaluate the influence of content popularity distribution, a heavy-tailed Zipf distribution and an Equal popularity distribution are evaluated. In addition, the work investigates the influence of downlink traffic behavior and power consumption parameters on optimum cluster sizes. Attained results reveal that maximum savings in energy consumption introduced by cluster-based collaborative caching are up to 34.3% and 21.8% under the Zipf and Equal distribution, respectively. Cache collaboration is not recommended when all core nodes contain fully replicated content servers. Results also show that power consumption parameters do not influence cluster formation. It is recommended keeping cache collaboration in the core network simple, so as to reduce intra-cluster communication.

Keywords: Artificial nodes, cluster formation, collaborative caching, intra-cluste communication, IP over WDM

DOI: 10.3233/JHS-230018

Journal: Journal of High Speed Networks, vol. 30, no. 1, pp. 97-114, 2024