Analyzing Performance Data Exchange in Content Delivery Networks

In a Content Delivery Network a set of geographically distributed surrogate servers, holding mirror copies of resources obtained from an origin server, are used to improve the perceived quality of a web portal. The Request Routing System is the component of a CDN responsible for both redirecting user requests to the best surrogate and collecting, usually from the surrogates themselves, the performance information needed to make redirection decisions. The accuracy of these performance information is very important in order to make right decisions that lead to an improvement of the Quality of Experience perceived by the users. In this paper we propose and evaluate algorithms for sending performance information in a CDN. The goal of the proposed algorithms is to guarantee the better performance information accuracy with the lowest possible impact on the network traffic. To the best of our knowledge, our work represents the first contribution in this research direction.