Optimizing Content Delivery in QoS-Aware Multi-CDNs

Broadband network technologies have improved the bandwidth of the edge of the Internet, but its core is still a bottleneck for large file transfers. Content Delivery Networks (CDNs), built at the edge of the Internet, are able to reduce the workload of network backbones, but their scalability and network reach is often limited, especially in case of QoS-bound delivery services. By using the emerging CDN internetworking, a CDN can dynamically exploit resources of other cooperating CDNs to face peak loads and temporary malfunctions without violating QoS levels negotiated with content providers. In this chapter, after a wide discussion of the problem, the authors propose an architectural schema and an algorithm, based on the divisible load theory, which optimizes delivery of large data files by satisfying an SLA, agreed with a content provider, while respecting the maximum budget that the delivering CDN can pay to peer CDNs to ensure its revenue.