Content multi-homing: An alternative approach

The CDN serves as an essential element in providing content delivery services on the Internet; however, limited by its footprint and influenced by variations of network conditions and user demands, no individual CDN can qualitatively fulfill delivery tasks anytime and anywhere. As such, large content providers often use multiple CDNs. Nevertheless, this approach is not only cumbersome to negotiate multiple business contracts, but also economically inefficient, especially for small content providers. A simpler alternative approach would be to let each content provider only sign one contract with an authoritative CDN, say CDN-0, and let CDN-0 handle the potential performance trap of individual CDN. To fulfill its business commitment, CDN-0 could either use its own infrastructure or rent services from other CDNs, which is sometimes indispensable. To make an optimal operating plan for CDN-0 operator, we propose a new problem, called MCDN-CM, whose objective is to minimize CDN-0´s operating cost. MCDN-CM is a concave minimization problem and we take advantage of the special form of the practical CDN-pricing function - piece-wise linear concave - to arrive at an optimal solution through an iterative procedure. We conduct numerical experiments under realistic settings and show via the experimental results that CDN-0 can achieve a tremendous cost-saving by using our proposed algorithm.