Stochastic Forecasts Achieve High Throughput and Low Delay ... · Stochastic Forecasts Achieve High...
Transcript of Stochastic Forecasts Achieve High Throughput and Low Delay ... · Stochastic Forecasts Achieve High...
![Page 1: Stochastic Forecasts Achieve High Throughput and Low Delay ... · Stochastic Forecasts Achieve High Throughput and Low Delay over Cellular Networks Keith Winstein, Anirudh Sivaraman,](https://reader030.fdocuments.in/reader030/viewer/2022041302/5e13529c7dfef550d35f1a79/html5/thumbnails/1.jpg)
Stochastic Forecasts Achieve High Throughputand Low Delay over Cellular Networks
Keith Winstein, Anirudh Sivaraman, and Hari Balakrishnan
M.I.T. CSAIL
http://alfalfa.mit.edu
April 5, 2013
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Cellular networks are variable
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Keith Winstein, Anirudh Sivaraman, and Hari Balakrishnan M.I.T. CSAIL http://alfalfa.mit.edu
Stochastic Forecasts Achieve High Throughput and Low Delay over Cellular Networks
![Page 3: Stochastic Forecasts Achieve High Throughput and Low Delay ... · Stochastic Forecasts Achieve High Throughput and Low Delay over Cellular Networks Keith Winstein, Anirudh Sivaraman,](https://reader030.fdocuments.in/reader030/viewer/2022041302/5e13529c7dfef550d35f1a79/html5/thumbnails/3.jpg)
Cellular networks are too reliable
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Round-triptime(s)
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(Verizon LTE, one TCP download.)
Keith Winstein, Anirudh Sivaraman, and Hari Balakrishnan M.I.T. CSAIL http://alfalfa.mit.edu
Stochastic Forecasts Achieve High Throughput and Low Delay over Cellular Networks
![Page 4: Stochastic Forecasts Achieve High Throughput and Low Delay ... · Stochastic Forecasts Achieve High Throughput and Low Delay over Cellular Networks Keith Winstein, Anirudh Sivaraman,](https://reader030.fdocuments.in/reader030/viewer/2022041302/5e13529c7dfef550d35f1a79/html5/thumbnails/4.jpg)
Interactive apps work poorly
I We measured cellular networks while driving:
I Verizon LTEI Verizon 3G (1xEV-DO)I AT&T LTEI T-Mobile 3G (UMTS)
I Then ran apps across replayed network trace:
I Skype (Windows 7)I Google Hangout (Chrome on Windows 7)I Apple Facetime (OS X)
Keith Winstein, Anirudh Sivaraman, and Hari Balakrishnan M.I.T. CSAIL http://alfalfa.mit.edu
Stochastic Forecasts Achieve High Throughput and Low Delay over Cellular Networks
![Page 5: Stochastic Forecasts Achieve High Throughput and Low Delay ... · Stochastic Forecasts Achieve High Throughput and Low Delay over Cellular Networks Keith Winstein, Anirudh Sivaraman,](https://reader030.fdocuments.in/reader030/viewer/2022041302/5e13529c7dfef550d35f1a79/html5/thumbnails/5.jpg)
Performance summary
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Skype
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Keith Winstein, Anirudh Sivaraman, and Hari Balakrishnan M.I.T. CSAIL http://alfalfa.mit.edu
Stochastic Forecasts Achieve High Throughput and Low Delay over Cellular Networks
![Page 6: Stochastic Forecasts Achieve High Throughput and Low Delay ... · Stochastic Forecasts Achieve High Throughput and Low Delay over Cellular Networks Keith Winstein, Anirudh Sivaraman,](https://reader030.fdocuments.in/reader030/viewer/2022041302/5e13529c7dfef550d35f1a79/html5/thumbnails/6.jpg)
Why is performance so bad?
I Exiting schemes react to congestion signals.
I Packet loss.I Increase in round-trip time.
I Feedback comes too late.
I The killer: self-inflicted queueing delay.
I Throughput overshoot means a queue filling up.
Keith Winstein, Anirudh Sivaraman, and Hari Balakrishnan M.I.T. CSAIL http://alfalfa.mit.edu
Stochastic Forecasts Achieve High Throughput and Low Delay over Cellular Networks
![Page 7: Stochastic Forecasts Achieve High Throughput and Low Delay ... · Stochastic Forecasts Achieve High Throughput and Low Delay over Cellular Networks Keith Winstein, Anirudh Sivaraman,](https://reader030.fdocuments.in/reader030/viewer/2022041302/5e13529c7dfef550d35f1a79/html5/thumbnails/7.jpg)
Sprout’s goal
I Most throughput
I Bounded risk of delay > 100 ms
Keith Winstein, Anirudh Sivaraman, and Hari Balakrishnan M.I.T. CSAIL http://alfalfa.mit.edu
Stochastic Forecasts Achieve High Throughput and Low Delay over Cellular Networks
![Page 8: Stochastic Forecasts Achieve High Throughput and Low Delay ... · Stochastic Forecasts Achieve High Throughput and Low Delay over Cellular Networks Keith Winstein, Anirudh Sivaraman,](https://reader030.fdocuments.in/reader030/viewer/2022041302/5e13529c7dfef550d35f1a79/html5/thumbnails/8.jpg)
Bounded risk of delay
I Infer link speed from interarrival distribution.
I Predict future link speed.
I Don’t wait for congestion.
I Control: Send as much as possible, but require:
I 95% chance all packets arrive within 100 ms.
Keith Winstein, Anirudh Sivaraman, and Hari Balakrishnan M.I.T. CSAIL http://alfalfa.mit.edu
Stochastic Forecasts Achieve High Throughput and Low Delay over Cellular Networks
![Page 9: Stochastic Forecasts Achieve High Throughput and Low Delay ... · Stochastic Forecasts Achieve High Throughput and Low Delay over Cellular Networks Keith Winstein, Anirudh Sivaraman,](https://reader030.fdocuments.in/reader030/viewer/2022041302/5e13529c7dfef550d35f1a79/html5/thumbnails/9.jpg)
Infer: link speed from flicker noise process
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(Verizon LTE, phone stationary.)
Keith Winstein, Anirudh Sivaraman, and Hari Balakrishnan M.I.T. CSAIL http://alfalfa.mit.edu
Stochastic Forecasts Achieve High Throughput and Low Delay over Cellular Networks
![Page 10: Stochastic Forecasts Achieve High Throughput and Low Delay ... · Stochastic Forecasts Achieve High Throughput and Low Delay over Cellular Networks Keith Winstein, Anirudh Sivaraman,](https://reader030.fdocuments.in/reader030/viewer/2022041302/5e13529c7dfef550d35f1a79/html5/thumbnails/10.jpg)
Predict: future link speed
I Model evolution of speed as random walk.
I (Brownian motion)
I Cautious forecast: 5th percentile cumulative packets
I Receiver makes forecast; sends back to sender in ack
I Almost all precalculated
Keith Winstein, Anirudh Sivaraman, and Hari Balakrishnan M.I.T. CSAIL http://alfalfa.mit.edu
Stochastic Forecasts Achieve High Throughput and Low Delay over Cellular Networks
![Page 11: Stochastic Forecasts Achieve High Throughput and Low Delay ... · Stochastic Forecasts Achieve High Throughput and Low Delay over Cellular Networks Keith Winstein, Anirudh Sivaraman,](https://reader030.fdocuments.in/reader030/viewer/2022041302/5e13529c7dfef550d35f1a79/html5/thumbnails/11.jpg)
Sprout’s model
Sender Queue Receiver
Poisson process
Rate λ controls
λ
σ
Brownian motion
λz
If in an outage,
drains queue
Poisson process
of σ√t varies λ λz is escape rate.
Keith Winstein, Anirudh Sivaraman, and Hari Balakrishnan M.I.T. CSAIL http://alfalfa.mit.edu
Stochastic Forecasts Achieve High Throughput and Low Delay over Cellular Networks
![Page 12: Stochastic Forecasts Achieve High Throughput and Low Delay ... · Stochastic Forecasts Achieve High Throughput and Low Delay over Cellular Networks Keith Winstein, Anirudh Sivaraman,](https://reader030.fdocuments.in/reader030/viewer/2022041302/5e13529c7dfef550d35f1a79/html5/thumbnails/12.jpg)
Parameters
Volatility σ: fixed @ 200 pkts/s√s
Expected outage time 1/λz : 1 sTick length: 20 msForecast length: 160 msDelay target: 100 msRisk tolerance: 5%
All source code was frozen before data collection began.
Keith Winstein, Anirudh Sivaraman, and Hari Balakrishnan M.I.T. CSAIL http://alfalfa.mit.edu
Stochastic Forecasts Achieve High Throughput and Low Delay over Cellular Networks
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Control: fill up 100 ms forecast window
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Keith Winstein, Anirudh Sivaraman, and Hari Balakrishnan M.I.T. CSAIL http://alfalfa.mit.edu
Stochastic Forecasts Achieve High Throughput and Low Delay over Cellular Networks
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Control: fill up 100 ms forecast window
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Keith Winstein, Anirudh Sivaraman, and Hari Balakrishnan M.I.T. CSAIL http://alfalfa.mit.edu
Stochastic Forecasts Achieve High Throughput and Low Delay over Cellular Networks
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Control: fill up 100 ms forecast window
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Keith Winstein, Anirudh Sivaraman, and Hari Balakrishnan M.I.T. CSAIL http://alfalfa.mit.edu
Stochastic Forecasts Achieve High Throughput and Low Delay over Cellular Networks
![Page 16: Stochastic Forecasts Achieve High Throughput and Low Delay ... · Stochastic Forecasts Achieve High Throughput and Low Delay over Cellular Networks Keith Winstein, Anirudh Sivaraman,](https://reader030.fdocuments.in/reader030/viewer/2022041302/5e13529c7dfef550d35f1a79/html5/thumbnails/16.jpg)
Control: fill up 100 ms forecast window
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Keith Winstein, Anirudh Sivaraman, and Hari Balakrishnan M.I.T. CSAIL http://alfalfa.mit.edu
Stochastic Forecasts Achieve High Throughput and Low Delay over Cellular Networks
![Page 17: Stochastic Forecasts Achieve High Throughput and Low Delay ... · Stochastic Forecasts Achieve High Throughput and Low Delay over Cellular Networks Keith Winstein, Anirudh Sivaraman,](https://reader030.fdocuments.in/reader030/viewer/2022041302/5e13529c7dfef550d35f1a79/html5/thumbnails/17.jpg)
Control: fill up 100 ms forecast window
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Keith Winstein, Anirudh Sivaraman, and Hari Balakrishnan M.I.T. CSAIL http://alfalfa.mit.edu
Stochastic Forecasts Achieve High Throughput and Low Delay over Cellular Networks
![Page 18: Stochastic Forecasts Achieve High Throughput and Low Delay ... · Stochastic Forecasts Achieve High Throughput and Low Delay over Cellular Networks Keith Winstein, Anirudh Sivaraman,](https://reader030.fdocuments.in/reader030/viewer/2022041302/5e13529c7dfef550d35f1a79/html5/thumbnails/18.jpg)
Control: fill up 100 ms forecast window
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Cautious fo
recast
Keith Winstein, Anirudh Sivaraman, and Hari Balakrishnan M.I.T. CSAIL http://alfalfa.mit.edu
Stochastic Forecasts Achieve High Throughput and Low Delay over Cellular Networks
![Page 19: Stochastic Forecasts Achieve High Throughput and Low Delay ... · Stochastic Forecasts Achieve High Throughput and Low Delay over Cellular Networks Keith Winstein, Anirudh Sivaraman,](https://reader030.fdocuments.in/reader030/viewer/2022041302/5e13529c7dfef550d35f1a79/html5/thumbnails/19.jpg)
Control: fill up 100 ms forecast window
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100 ms100 ms
Cautious fo
recast
Keith Winstein, Anirudh Sivaraman, and Hari Balakrishnan M.I.T. CSAIL http://alfalfa.mit.edu
Stochastic Forecasts Achieve High Throughput and Low Delay over Cellular Networks
![Page 20: Stochastic Forecasts Achieve High Throughput and Low Delay ... · Stochastic Forecasts Achieve High Throughput and Low Delay over Cellular Networks Keith Winstein, Anirudh Sivaraman,](https://reader030.fdocuments.in/reader030/viewer/2022041302/5e13529c7dfef550d35f1a79/html5/thumbnails/20.jpg)
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Verizon LTE Downlink
Skype
Bette
r
Keith Winstein, Anirudh Sivaraman, and Hari Balakrishnan M.I.T. CSAIL http://alfalfa.mit.edu
Stochastic Forecasts Achieve High Throughput and Low Delay over Cellular Networks
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Verizon LTE Downlink
SkypeFacetime
Google Hangout
Bette
r
Keith Winstein, Anirudh Sivaraman, and Hari Balakrishnan M.I.T. CSAIL http://alfalfa.mit.edu
Stochastic Forecasts Achieve High Throughput and Low Delay over Cellular Networks
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Verizon LTE Downlink
Compound TCP
LEDBAT
SkypeFacetime
Google Hangout
Vegas
Bette
r
Keith Winstein, Anirudh Sivaraman, and Hari Balakrishnan M.I.T. CSAIL http://alfalfa.mit.edu
Stochastic Forecasts Achieve High Throughput and Low Delay over Cellular Networks
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Verizon LTE Downlink
Compound TCP
LEDBAT
Cubic
SkypeFacetime
Google Hangout
Vegas
Bette
r
Keith Winstein, Anirudh Sivaraman, and Hari Balakrishnan M.I.T. CSAIL http://alfalfa.mit.edu
Stochastic Forecasts Achieve High Throughput and Low Delay over Cellular Networks
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SkypeFacetime
Google Hangout
Vegas
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Bette
r
Keith Winstein, Anirudh Sivaraman, and Hari Balakrishnan M.I.T. CSAIL http://alfalfa.mit.edu
Stochastic Forecasts Achieve High Throughput and Low Delay over Cellular Networks
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Verizon LTE Downlink
Sprout-EWMA
Compound TCP
LEDBAT
Cubic
SkypeFacetime
Google Hangout
Vegas
Sprout
Bette
r
Keith Winstein, Anirudh Sivaraman, and Hari Balakrishnan M.I.T. CSAIL http://alfalfa.mit.edu
Stochastic Forecasts Achieve High Throughput and Low Delay over Cellular Networks
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LEDBAT
Cubic
Skype Facetime
Google Hangout
Vegas
Sprout
Keith Winstein, Anirudh Sivaraman, and Hari Balakrishnan M.I.T. CSAIL http://alfalfa.mit.edu
Stochastic Forecasts Achieve High Throughput and Low Delay over Cellular Networks
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Cubic
Skype
FacetimeGoogle Hangout
Vegas
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Keith Winstein, Anirudh Sivaraman, and Hari Balakrishnan M.I.T. CSAIL http://alfalfa.mit.edu
Stochastic Forecasts Achieve High Throughput and Low Delay over Cellular Networks
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Cubic
Skype
Facetime
Google Hangout
Vegas
Sprout
Keith Winstein, Anirudh Sivaraman, and Hari Balakrishnan M.I.T. CSAIL http://alfalfa.mit.edu
Stochastic Forecasts Achieve High Throughput and Low Delay over Cellular Networks
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Google Hangout
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Keith Winstein, Anirudh Sivaraman, and Hari Balakrishnan M.I.T. CSAIL http://alfalfa.mit.edu
Stochastic Forecasts Achieve High Throughput and Low Delay over Cellular Networks
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LEDBATCubic
SkypeFacetime
Google Hangout
Vegas
Sprout
Keith Winstein, Anirudh Sivaraman, and Hari Balakrishnan M.I.T. CSAIL http://alfalfa.mit.edu
Stochastic Forecasts Achieve High Throughput and Low Delay over Cellular Networks
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Cubic
SkypeFacetime
Google Hangout
Vegas
Sprout
Keith Winstein, Anirudh Sivaraman, and Hari Balakrishnan M.I.T. CSAIL http://alfalfa.mit.edu
Stochastic Forecasts Achieve High Throughput and Low Delay over Cellular Networks
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Sprout-EWMA
Compound TCP
LEDBAT
Cubic
Skype
Facetime
Google Hangout
Vegas
Sprout
Keith Winstein, Anirudh Sivaraman, and Hari Balakrishnan M.I.T. CSAIL http://alfalfa.mit.edu
Stochastic Forecasts Achieve High Throughput and Low Delay over Cellular Networks
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Overall results
Sprout vs. Avg. speedup Delay reduction
Skype 2.2× 7.9×Hangout 4.4× 7.2×Facetime 1.9× 8.7×Compound 1.3× 4.8×TCP Vegas 1.1× 2.1×LEDBAT Same 2.8×Cubic 0.91× 79×
Keith Winstein, Anirudh Sivaraman, and Hari Balakrishnan M.I.T. CSAIL http://alfalfa.mit.edu
Stochastic Forecasts Achieve High Throughput and Low Delay over Cellular Networks
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Varying risk tolerance
200
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2003005001000300050001000030000
Th
rou
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bp
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Self-inflicted delay (ms)
Compound TCP
LEDBAT
Cubic
Skype
Facetime
Google Hangout
Vegas
Sprout (5%)
25%
50%
75%
95%
Keith Winstein, Anirudh Sivaraman, and Hari Balakrishnan M.I.T. CSAIL http://alfalfa.mit.edu
Stochastic Forecasts Achieve High Throughput and Low Delay over Cellular Networks
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Competes with AQM even though end-to-end
0
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2003005001000300050001000030000
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Sprout
Sprout-EWMA
Cubic
Cubic-over-CoDel
Keith Winstein, Anirudh Sivaraman, and Hari Balakrishnan M.I.T. CSAIL http://alfalfa.mit.edu
Stochastic Forecasts Achieve High Throughput and Low Delay over Cellular Networks
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Competing traffic inside Sprout tunnel
Direct via Sprout Benefit
Cubic throughput 8336 kbps 3776 kbps 0.5× (= worse)Skype throughput 78 kbps 490 kbps 6×Skype 95% delay 6.0 s 0.17 s 35×
Keith Winstein, Anirudh Sivaraman, and Hari Balakrishnan M.I.T. CSAIL http://alfalfa.mit.edu
Stochastic Forecasts Achieve High Throughput and Low Delay over Cellular Networks
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Replication by Stanford students (February–March 2013)
I Alterman & Quach reproduced some of our measurements
I http://ReproducingNetworkResearch.wordpress.com/2013/03/12/1216/
I Won best project award in Stanford networking class!
Keith Winstein, Anirudh Sivaraman, and Hari Balakrishnan M.I.T. CSAIL http://alfalfa.mit.edu
Stochastic Forecasts Achieve High Throughput and Low Delay over Cellular Networks
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M.I.T. 6.829 contest (March–April 2013)
I Turnkey network emulator, evaluation
I Sender, receiver run in Linux containers
I 4th prize: $20
I 3rd prize: $30
I 2nd prize: $40
I (If beat Sprout) 1st prize:
Co-authorship on future paper
Keith Winstein, Anirudh Sivaraman, and Hari Balakrishnan M.I.T. CSAIL http://alfalfa.mit.edu
Stochastic Forecasts Achieve High Throughput and Low Delay over Cellular Networks
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M.I.T. 6.829 contest (March–April 2013)
I Turnkey network emulator, evaluation
I Sender, receiver run in Linux containers
I 4th prize: $20
I 3rd prize: $30
I 2nd prize: $40
I (If beat Sprout) 1st prize: Co-authorship on future paper
Keith Winstein, Anirudh Sivaraman, and Hari Balakrishnan M.I.T. CSAIL http://alfalfa.mit.edu
Stochastic Forecasts Achieve High Throughput and Low Delay over Cellular Networks
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Baseline
Keith Winstein, Anirudh Sivaraman, and Hari Balakrishnan M.I.T. CSAIL http://alfalfa.mit.edu
Stochastic Forecasts Achieve High Throughput and Low Delay over Cellular Networks
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Land of 3,000 student protocols
Keith Winstein, Anirudh Sivaraman, and Hari Balakrishnan M.I.T. CSAIL http://alfalfa.mit.edu
Stochastic Forecasts Achieve High Throughput and Low Delay over Cellular Networks
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Sprout is on the frontier
Keith Winstein, Anirudh Sivaraman, and Hari Balakrishnan M.I.T. CSAIL http://alfalfa.mit.edu
Stochastic Forecasts Achieve High Throughput and Low Delay over Cellular Networks
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Limitations
I Only evaluated long-running flows.
I All testing data from Boston.
I User should wrap competing flows inside Sprout.
I If queue is full of another user’s packets, an end-to-endscheme can’t help.
I Fortunately, cells have per-device queues. . .I . . . but Wi-Fi generally doesn’t.
I What about when the cell link isn’t the bottleneck?
Keith Winstein, Anirudh Sivaraman, and Hari Balakrishnan M.I.T. CSAIL http://alfalfa.mit.edu
Stochastic Forecasts Achieve High Throughput and Low Delay over Cellular Networks
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Our approach
I Pick a model, any model.
I All models are wrong, but they help anyway!
I See if it lands on the frontier.*
* (On a large set of real network paths or newly-collectedtraces.)
I Kaizen for congestion
Keith Winstein, Anirudh Sivaraman, and Hari Balakrishnan M.I.T. CSAIL http://alfalfa.mit.edu
Stochastic Forecasts Achieve High Throughput and Low Delay over Cellular Networks
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Thank you
I Lakshminarayanan Subramanian
I Shuo Deng
I Jonathan Perry
I Katrina LaCurts
I Andrew McGregor
I Tim Shepard
I Dave Taht
I Michael Welzl
I Hannes Tschofenig
I Wireless@MIT members (http://wireless.csail.mit.edu)
I NSF & Shannon family (fellowship)
Keith Winstein, Anirudh Sivaraman, and Hari Balakrishnan M.I.T. CSAIL http://alfalfa.mit.edu
Stochastic Forecasts Achieve High Throughput and Low Delay over Cellular Networks
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Sprout for controlled delay over cellular networks
I Infer link speed from interarrival distribution
I Predict future link speed
I Control risk of large delay with cautious forecast
I Yields 2–4× throughput of Skype, Facetime, Hangout
I Achieves 7–9× reduction in self-inflicted delay
I Matches active queue management without router changes
I Code and directions at http://alfalfa.mit.edu
Keith Winstein, Anirudh Sivaraman, and Hari Balakrishnan M.I.T. CSAIL http://alfalfa.mit.edu
Stochastic Forecasts Achieve High Throughput and Low Delay over Cellular Networks