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Provider-aided Distance Information System (PaDIS)
Today, a large fraction of Internet traffic is
originating from Content Delivery Networks (CDN). To cope with the
increasing demand for content, CDNs deploy massively distributed
server infrastructures. Thus the content hosted by CDNS is available
at different locations on the Internet. To minimize their cost, CDNs
perform their own traffic optimization by assigning end-users to their
servers. Such an assignment made by the CDN is at large unaware of the
network conditions and is based on inaccurate information about the
location of the end-user. Thus, users are not always assigned to the
CDN servers that lead to optimal end-user performance. In contrast, an
ISP has detailed and accurate knowledge about the status of its own
network. However, today ISPs are unable to utilize their knowledge as
there are no mechanisms available to influence the assignment of users
to CDN servers.
To improve user assignment, especially from a performance perspective, we propose and deploy a Provider-aided Distance Information System (PaDIS). PaDIS is a novel system operated by an ISP that allows ISPs to influence the assignment of users to servers by utilizing information available only to ISPs as well as by exploiting server diversity exposed by the CDN server selection process. PaDIS ranks any user and available CDN server pair based on current network conditions and accurate network locations. It then returns back the most preferable servers to the end-user regarding a performance metric chosen by the ISP. As a result, PaDIS utilizes the deployed CDN server infrastructure to improve end-user performance.
To evaluate the performance improvements we have implemented and deployed a PaDIS prototype. Our field test results show that significant improvements in download time up to a factor of four for content offered by popular content distributors can be achieved when PaDIS is used.