We present PaDIS Emulator, a fully automated platform to evaluate CDN-ISP collaboration for better content delivery, traffic engineering, and cost reduction. The PaDIS Emulator enables researchers as well as CDN and ISP operators to evaluate the benefits of collaboration using their own operational networks, configuration, and cost functions.

Recent studies show that a large fraction of Internet traffic is originated by Content Providers (CPs) such as content distribution networks and hyper-giants. To cope with the increasing demand for content, CPs deploy massively distributed server infrastructures. Thus, content is available in many network locations and can be downloaded by traversing different paths in a network. Despite the prominent server location and path diversity, the decisions on how to map users to servers by CPs and how to perform traffic engineering by ISPs, are independent. This leads to a lose-lose situation as CPs are not aware about the network bottlenecks nor the location of end-users, and the ISPs struggle to cope with rapid traffic shifts caused by the dynamic CP server selection process.

Content delivery systems constitute a major portion of today’s In-ternet traffic. While they are a good source of revenue for Internet Service Providers (ISPs), the huge volume of content delivery traf-fic also poses a significant burden and traffic engineering challenge for the ISP. The difficulty is due to the immense volume of trans-fers, while the traffic engineering challenge stems from the fact that most content delivery systems themselves utilize a distributed infrastructure. They perform their own traffic flow optimization and realize this using the DNS system. While content delivery sys-tems may, to some extent, consider the user’s performance within their optimization criteria, they currently have no incentive to con-sider any of the ISP’s constraints. As a consequence, the ISP has “lost control ” over a major part of its traffic. To overcome this im-pairment, we propose a solution where the ISP offers a Provider-aided Distance Information System (PaDIS). PaDIS uses informa-tion available only to the ISP to rank any client-host pair based on distance information, such as delay, bandwidth or number of hops. In this paper we show that the applicability of the system is sig-nificant. More than 70 % of the HTTP traffic of a major European ISP can be accessed via multiple different locations. Moreover, we show that deploying PaDIS is not only beneficial to ISPs, but also to users. Experiments with different content providers show that improvements in download times of up to a factor of four are possible. Furthermore, we describe a high performance implemen-tation of PaDIS and show how it can be deployed within an ISP.