Optimised balancing algorithm for content delivery networks

Abstract

In this study the authors present the ‘fictitiously starred optimised balancing’ (FSOB), a novel algorithm for load balancing in a content delivery network (CDN) scenario. FSOB exploits the multiple redirection mechanism of the HTTP protocol to optimally redistribute clients requests among the servers which build up the CDN. Load redistribution is aimed at equalising the level of occupancy of the server queues and is achieved through the periodical exchange of information computed locally at each node. The algorithm initially makes a fictitious assumption about the local topology of the network, as it is seen by each single server node, which looks at itself as the centre (i.e. the master) of a star made up of all of its neighbours (i.e. the slaves). Load redistribution is performed by the master which, if needed, appropriately redirects incoming requests to its slaves. The authors show how FSOB outperforms most of its competitors under a number of fundamental aspects, at the price of an increased overhead owing to the adoption of the multiple redirections mechanism for the redistribution phase. Finally, they study the scalability properties of FSOB and perform a comparative evaluation of its performance with respect to the most interesting existing solutions.