Definition and performance evaluation of a request routing algorithm to distribute digital cinema contents

In this work, carried out in the framework of the IST Project EDCINE, we deal with the network distribution of Digital Cinema contents, through a Content Delivery Network, towards theatres. One of the main criticalities of the system is the very large size of the contents to be transferred while respecting the maximum download time requirements. From the operator perspective, this criticality translates into the objective of optimizing the usage of network resources while complying with QoS constraints. The goal of this paper is first to present the network architecture and procedures relevant to the distribution service, and to specifically analyse the problem of service request routing (4-7 routing), whose objective is to select a set of servers to satisfy a content request efficiently. In particular, we focus on the definition of the mathematical model of the problem of minimising the network operational cost of the content distribution. Since some known professional, optimisation tools are not able to find the global optimum even in very simple configurations, we propose a heuristic approach based on the min-plus convolution. Preliminary numerical results show that such an algorithm outperforms the selected professional tools, while maintaining an affordable computation time.