BBR: Congestion-Based Congestion Control (paper review)

CS597s seminar discussion at Princeton. Slides: https://kyleatprinceton.github.io/cos... Paper: https://queue.acm.org/detail.cfm?id=3... Authors from Google: Neal Cardwell, Yuchung Cheng, C. Stephen Gunn, Soheil Hassas Yeganeh, Van Jacobson Abstract By all accounts, today’s Internet is not moving data as well as it should. Most of the world’s cellular users experience delays of seconds to minutes; public Wi-Fi in airports and conference venues is often worse. Physics and climate researchers need to exchange petabytes of data with global collaborators but find their carefully engineered multi-Gbps infrastructure often delivers at only a few Mbps over intercontinental distances.6 These problems result from a design choice made when TCP congestion control was created in the 1980s—interpreting packet loss as “congestion.”13 This equivalence was true at the time but was because of technology limitations, not first principles. As NICs (network interface controllers) evolved from Mbps to Gbps and memory chips from KB to GB, the relationship between packet loss and congestion became more tenuous. Today TCP’s loss-based congestion control—even with the current best of breed, CUBIC—is the primary cause of these problems. When bottleneck buffers are large, loss-based congestion control keeps them full, causing bufferbloat. When bottleneck buffers are small, loss-based congestion control misinterprets loss as a signal of congestion, leading to low throughput. Fixing these problems requires an alternative to loss-based congestion control. Finding this alternative requires an understanding of where and how network congestion originates. 00:00:00 Intro 00:00:43 Context: congestion control 00:02:09 Problem Statement 00:02:20 New TCP Reno 00:02:58 CUBIC 00:03:39 Key Idea 00:05:00 How BBR works 00:07:06 BBR's Design 00:14:05 Evaluation 00:27:56 Deployment at Google 00:28:46 Future work 00:29:25 My Opinion #computernetworking #computerscience #paperreview