Re: [Bloat] BBR talk from Stony Brook University

[David Collier-Brown <davecb.42@gmail.com>]

On 2020-12-12 1:11 p.m., Rich Brown wrote:
> Google Alerts for "bufferbloat" pointed to this talk at Stony Brook 
> University in New York State:
>
> Dates: Thursday, December 17, 2020 - 12:30pm to 2:00pm (US EST: UTC-5)
> Location: Zoom - contact events@cs.stonybrook.edu for Zoom info.
>
> Abstract: BBR is a new congestion control algorithm and is seeing 
> increased adoption especially for video traffic. BBR solves the 
> bufferbloat problem in legacy loss-based congestion control algorithms 
> where application performance drops considerably when router buffers 
> are deep. BBR regulates traffic such that router queues don’t build up 
> to avoid the bufferbloat problem while still maintaining high 
> throughput. Though BBR is able to combat bufferbloat for sustained 
> steady traffic such as large file downloads, our analysis shows that 
> video applications experience significantly poor performance when 
> using BBR under deep buffers. In fact, we find that video traffic sees 
> inflated latencies because of long queues at the router, ultimately 
> degrading video performance.
>
> In this talk, I will present our work on the interaction between BBR 
> and streaming video. We investigate the relationship between network 
> metrics such as delay and delivery rate during the video run and the 
> quality of subsequent video segments. However, we find only weak 
> correlations, suggesting that another factor is at play. Our empirical 
> investigation reveals that BBR under deep buffers and high network 
> burstiness severely overestimates available bandwidth and is slower to 
> converge to steady state, both of which result in BBR sending 
> substantially more data into the network, causing a queue buildup. 
> This elevated packet sending rate under BBR is ultimately caused by 
> the router’s ability to absorb bursts in traffic, which destabilizes 
> BBR’s bandwidth estimation and overrides BBR’s expected logic for 
> exiting the startup phase.
>
> Original Notice: 
> https://www.cs.stonybrook.edu/Rebecca-Drucker-Research-Proficiency-Presentation-Investigating-BBR-Bufferbloat-Problem-DASH-Video
>
>
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Ms Drucker is in their PhD program, as you might guess, mentioned in 
https://www3.cs.stonybrook.edu/~csgso/eboard.html#


Rebecca is a 3rd year PhD student working in the NetSys lab with 
Professor Aruna Balasubramanian. Her research involves optimizing web 
performance at the application and transport layers, particularly for 
streaming video. She enjoys hiking, cross stitching, and watching true 
crime television shows.

-- 
David Collier-Brown,         | Always do right. This will gratify
System Programmer and Author | some people and astonish the rest
davecb@spamcop.net           |                      -- Mark Twain