Content delivery systems constitute a major portion of today's Internet
traffic. While they are a good source of revenue for Internet Service
Providers (ISPs), the huge volume of content delivery traffic also poses a
significant burden and traffic engineering challenge for the ISP. The
difficulty is due to the immense volume of transfers, 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 systems may, to some extent, consider the user's
performance within their optimization criteria, they currently have no
incentive to consider any of the ISP's constraints. As a consequence, the ISP
has ``lost control'' over a major part of its traffic. To overcome this impairment, we
propose a solution where the ISP offers a Provider-aided Distance
Information System (PaDIS). PaDIS uses information 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 significant. 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 implementation of PaDIS and show how it can be deployed within an ISP.