Practical, Real-time Centralized Control for CDN-based Live Video Delivery

Live video delivery is expected to reach a peak of 50 Tbps this year [7]. This surging popularity is funda-mentally changing the Internet video delivery landscape. CDNs must meet users ’ demands for fast join times, high bitrates, and low buffering ratios, while minimizing their own cost of delivery and responding to issues in real-time. Wide-area latency, loss, and failures, as well as varied workloads (“mega-events ” to long-tail), make meeting these demands challenging. An analysis of video sessions [32] concluded that a centralized controller could improve user experience, but CDN systems have shied away from such designs due to the difficulty of quickly handling failures [29], a require-ment of both operators and users. We introduce VDN, a practical approach to a video delivery network that uses a centralized algorithm for live video optimization. VDN provides CDN operators with real-time, fine-grained con-trol. It does this in spite of challenges resulting from the wide-area (e.g., state inconsistency, partitions, failures) by using a hybrid centralized+distributed control plane, increasing average bitrate by 1.7 × and decreasing cost by 2 × in different scenarios. CCS Concept