Invited Abstract: A Simulation Package for Energy Consumption of Content Delivery Networks (CDNs)

Content Delivery Networks (CDNs) are becoming an integral part of the future generation Internet. Traditionally, these networks have been designed with the goals of traffic offload and the improvement of users' quality of experience (QoE), but the energy consumption is also becoming an indispensable design factor for CDNs to be a sustainable solution. To study and improve the CDN architectures using this new design metric, we are planning to develop a generic and flexible simulation package in OMNet++. This package is aimed to render a holistic view about the CDN energy consumption behaviour by incorporating the state-of-the-art energy consumption models proposed for the individual elements of CDNs (e.g. servers, routers, wired and wireless links, wireless devices, etc.) and for the various Internet contents (web pages, files, streaming video, etc.). I. INTRODUCTION With the tremendous growth of the Internet traffic and the demand for guaranteed quality of service, the content delivery networks (CDNs) have emerged as a promising solution to offload the traffic and to reduce content access delay, so that both content providers and consumers benefit directly. There is also a new emerging design goal for CDNs, motivated by the present trend of energy consumption in the ICT sector which implies for an urgent need for re-assessing and re-designing Internet systems to achieve energy efficient architectures. In particular, the content delivery networks can play a significant role in harnessing energy consumption per bit delivered to the end users. This is supported by the fact that the Internet is experiencing an unprecedented growth in the type and volume of contents. The most significant phenomenon of this type is video traffic. A recent trend of the Internet usage indicates an increased demand for streaming media (IPTV, Youtube etc.) in the downlink as well as an increased user generated traffic (upload of video to Facebook, Youtube, Vimeo etc.) in the uplink side. Knowing the fact that the delivery of video contents is highly bandwidth and processor demanding, it is of prominent value to understand how the current CDNs behave in terms of energy efficiency, and how to calibrate the existing CDNs or to design new ones by taking into account the energy efficiency as an additional design metric. The study of energy efficiency of the existing CDNs and, more importantly, the design of new CDNs require that the contributions of a tremendous number of factors to the energy consumption is taken into consideration. On one side, the end-users are increasingly inclined to use battery powered mobile devices or portable computers. On the other side, there are a huge number of network elements (e.g. servers, storages, routers, links, etc.) responsible for providing, managing, and carrying the Internet contents to the users. Therefore, the performance study of a given CDN architecture requires that the entire set of network elements with a role in carrying contents from a content provider to the consumers are taken into account. Moreover, contents have different types and properties and users have different preferences over contents and use different devices to access those contents. With this extremely huge set of elements involved in a CDN, simulation as a tool appears as the most affordable way of studying the energy efficiency of the existing CDNs, and to design new CDNs with respect to energy efficiency metric. In the following, we present the building blocks of an envisioned simulation package for the studying of energy consumption behaviour of CDNs.