Consistent Dynamic CDN Server Assignment for Online Video Streaming with Optimality Guarantees
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Server assignment plays an essential part in Content Delivery Network (CDN) to accelerate content distribution, especially for online video content, which is responsible for choosing a surrogate server to provide the best Quality of Service (QoS) for clients and balancing the server load. But it faces two critical challenges in practical: 1) dynamic server assignment may bring about a huge amount of video content migration among servers. 2) the constraint of DNS schedule granularity makes it difficult to distribute client demands in arbitrary proportion. To address these issues, we design a consistent dynamic server assignment algorithm, DynDNS. It gives a more "sticky" solution that can be easily implemented in DNS-based load balancing while keeping the overall QoS and server load satisfying. To the best of our knowledge, this is the first quantitative model for the dynamic DNS server assignment problem. Theoretical analysis proves that the proposed greedy algorithm has considerable optimality guarantees, and evaluation shows that DynDNS can avoid about 50 shift in demand allocation and yield more stable cache hit ratio.
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