Many large content publishers use multiple content distribution networks to deliver their content, and many commercial systems have become available to help a broader set of content publishers to benefit from using multiple distribution networks, which we refer to as content multihoming. In this paper, we conduct the first systematic study on optimizing content multihoming, by introducing novel algorithms to optimize both performance and cost for content multihoming. In particular, we design a novel, efficient algorithm to compute assignments of content objects to content distribution networks for content publishers, considering both cost and performance. We also design a novel, lightweight client adaptation algorithm executing at individual content viewers to achieve scalable, fine-grained, fast online adaptation to optimize the quality of experience (QoE) for individual viewers. We prove the optimality of our optimization algorithms and conduct systematic, extensive evaluations, using real charging data, content viewer demands, and performance data, to demonstrate the effectiveness of our algorithms. We show that our content multihoming algorithms reduce publishing cost by up to 40%. Our client algorithm executing in browsers reduces viewer QoE degradation by 51%.

Network faults such as link failures and high switch configuration delays can cause heavy congestion and packet loss. Because it takes time for the traffic engineering systems to detect and react to such faults, these conditions can last long-even tens of seconds. We propose forward fault correction (FFC), a proactive approach for handling faults. FFC spreads network traffic such that freedom from congestion is guaranteed under arbitrary combinations of up to k faults. We show how FFC can be practically realized by compactly encoding the constraints that arise from this large number of possible faults and solving them efficiently using sorting networks. Experiments with data from real networks show that, with negligible loss in overall network throughput, FFC can reduce data loss by a factor of 7-130 in well-provisioned networks, and reduce the loss of high-priority traffic to almost zero in wellutilized networks.