Building Economic Efficiency into Multicast Content Delivery Networks

摘要

Internet-scale dissemination of streaming contents (e.g. live sport games) is most successfully being provided by Multicast Content Delivery Networks (Multicast CDN). Multicast CDN is composed of dedicated servers placed strategically over the Internet, which forward content from origin site to end users. Multicast CDN delivers huge amount of data traffic, and therefore its major operational cost is the ISP cost for network access. Existing Multicast CDNs route user requests to most suitable server based on application performance, such as network delay, server throughput, Internet path congestion etc., without taking into account the potentially high ISP cost it may incur. Multicast CDNs need to control their ISP cost to remain commercially competitive since ISP cost is the most indicative factor affecting the pricing of their services. In this work, we present novel Multicast CDN Request Routing algorithms that minimize ISP cost while still maintaining good network performance for users. Multicast CDN Request Routing algorithms control majority of traffic assigned to servers and therefore directly impacts the ISP cost. ISP cost and user network performances are orthogonal metrics of performance and in order to balance the trade-off between them we introduce overall delay as a constraint to the Multicast CDN Request Routing algorithm. Multicast CDNs are business customers of ISPs and therefore can independently choose to reduce their bills by considering the ways in which ISPs charge. We have designed Request Routing algorithms that exploit the economy of scale in ISP charging function in assigning users to servers. We have developed Request Routing algorithms that exploit the nature of Percentile-based charging used by ISPs to compute the charging volume for traffic generated at server sites. Multicast CDN can cooperate with ISPs to reduce the operational cost of both the parties. Multicast CDN controls how traffic is redirected on the overlay, and that can conflict with how underlying ISPs want the traffic to be forwarded. We have developed Request Routing algorithms that assign users to servers that are available over cheaper IP routes. This reduces the transmission costs for ISPs and these savings can be transferred onto Multicast CDN.