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Broadband Internet Performance : A View from the Gateway

Broadband Internet Performance : A View from the Gateway. Srikanth Sundaresan, Walter de Donato , Nick Feamster , Renata Teixeira, Sam Crawford, Antonio Pescapè. Georgia Tech. University of Napoli. CNRS/UPMC Sorbonne Universités. SamKnows. What Affects Broadband Performance?.

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Broadband Internet Performance : A View from the Gateway

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  1. Broadband Internet Performance: A View from the Gateway

    Srikanth Sundaresan, Walter de Donato, Nick Feamster,Renata Teixeira, Sam Crawford, Antonio Pescapè Georgia Tech University of Napoli CNRS/UPMC Sorbonne Universités SamKnows
  2. What Affects Broadband Performance? Notion of performance is fuzzy What metrics should we measure? How to measure them? Important for regulators, consumers, ISPs, content providers 500ms delay causes 20% decrease in Google search traffic Broadband Internet Performance: A View from the Gateway IRTF ANRP, Atlanta, November 2012
  3. Accurate Measurements are Difficult Last Mile ISP Network End host measurements are not continuous, and affected by confounding factors Broadband Internet Performance: A View from the Gateway IRTF ANRP, Atlanta, November 2012
  4. The Case For the Gateway Measured average: 2.85 Mbps Down, 338 Kbps Up Actual Service plan: AT&T DSL 3 Mbps Down,384Kbps Up Gateway enables periodic measurements, and can account for confounding factors Broadband Internet Performance: A View from the Gateway IRTF ANRP, Atlanta, November 2012
  5. The Deployments Last Mile Internet SamKnows/BISmark Nearby Server Breadth: The FCC/SamKnows study 7,800 gateways, 18 ISPs, multiple service plans Depth: The BISmark study 120+ gateways in 28 countries worldwide, periodic and on-demand measurements Broadband Internet Performance: A View from the Gateway IRTF ANRP, Atlanta, November 2012
  6. Results: Overview Throughput: Depending on technique, results can vary up to 25% Traffic shaping varies across users, affects results Latency: Access link characteristics introduce loss/latency/throughput trade-offs Modem buffers can induce latencies up to 10 seconds Application Performance – Web: Latency becomes bottleneck beyond 16 Mbits/s Broadband Internet Performance: A View from the Gateway IRTF ANRP, Atlanta, November 2012
  7. Results: Overview Throughput: Depending on technique, results can vary up to 25% Traffic shaping varies across users, affects results Latency: Access link characteristics introduce loss/latency/throughput trade-offs Modem buffers can induce latencies up to 10 seconds Application Performance – Web: Latency becomes bottleneck beyond 16Mbits/s Broadband Internet Performance: A View from the Gateway IRTF ANRP, Atlanta, November 2012
  8. Interpreting Throughput Results Different techniques measure different aspects of throughput Broadband Internet Performance: A View from the Gateway IRTF ANRP, Atlanta, November 2012
  9. Traffic Shaping: PowerBoost Cable companies advertise “PowerBoost” Short bursts of high bandwidth Non-existent in DSL Broadband Internet Performance: A View from the Gateway IRTF ANRP, Atlanta, November 2012
  10. Traffic Shaping Varies Across Users Short-term throughput significantly different from sustainable throughput Broadband Internet Performance: A View from the Gateway IRTF ANRP, Atlanta, November 2012
  11. Results: Overview Throughput: Depending on technique, results can vary up to 25% Traffic shaping varies across users, affects results Latency: Access link characteristics introduce loss/latency/throughput trade-offs Modem buffers can induce latencies up to 10 seconds Application Performance – Web: Latency becomes bottleneck beyond 16 Mbits/s Broadband Internet Performance: A View from the Gateway IRTF ANRP, Atlanta, November 2012
  12. Latency Measurements Broadband Internet Performance: A View from the Gateway IRTF ANRP, Atlanta, November 2012
  13. Impact of Last-mile on Latency Cable ISPs DSL ISPs DSL last-mile latencies can be very high – 20% of users > 40ms for some ISPs Broadband Internet Performance: A View from the Gateway IRTF ANRP, Atlanta, November 2012
  14. DSL Interleaving Affects Latency Fastpath vs. Interleaved last-mile data path 9 8 7 6 5 4 3 2 1 Fastpath sends data in order, can recover from single losses Fastpath is susceptible to bursty loss 9 6 3 8 5 2 7 4 1 Extra Delay Interleaving sends data out-of-order, can recover from bursty loss Broadband Internet Performance: A View from the Gateway IRTF ANRP, Atlanta, November 2012
  15. Example: Latency-Throughput Tradeoff Both users have same service plan User 2: high latency, low loss 2.5 Throughput (Mbits/s) Interleaving decreases loss, increases latency, improves throughput User 1: low latency, high loss 2.2 30 10 Latency (ms) Broadband Internet Performance: A View from the Gateway IRTF ANRP, Atlanta, November 2012 Interleaving creates a trade-off between latency and throughput
  16. Modem Buffers are Too Large 10 seconds! Service plans can interact badly with modem buffers Broadband Internet Performance: A View from the Gateway IRTF ANRP, Atlanta, November 2012
  17. Results: Overview Throughput: Depending on technique, results can vary up to 25% Traffic shaping varies across users, affects results Latency: Access link characteristics introduce loss/latency/throughput trade-offs Modem buffers can induce latencies up to 10 seconds Application Performance – Web: Latency becomes bottleneck beyond 16 Mbits/s Broadband Internet Performance: A View from the Gateway IRTF ANRP, Atlanta, November 2012
  18. Implications: Web Performance Page load times can exceed 3 seconds – even for popular sites Broadband Internet Performance: A View from the Gateway IRTF ANRP, Atlanta, November 2012
  19. More Throughput Isn’t Everything Page load times stop improving Broadband Internet Performance: A View from the Gateway IRTF ANRP, Atlanta, November 2012 Page load times stop improving above about 8-16 Mbit/s
  20. Last-Mile Latency Matters Page load times increase with last mile latency Broadband Internet Performance: A View from the Gateway IRTF ANRP, Atlanta, November 2012
  21. Results: Summary Throughput: Depending on technique, results can vary up to 25% Traffic shaping varies across users, affects results Latency: Access link characteristics introduce loss/latency/throughput trade-offs Modem buffers can induce latencies up to 10 seconds Application Performance – Web: Latency becomes bottleneck beyond 16 Mbits/s Broadband Internet Performance: A View from the Gateway IRTF ANRP, Atlanta, November 2012
  22. Future Work Performance monitoring from the edge Effect of peering on performance Effect of CDN location, traffic engineering on application performance Effect of home wireless networks on performance Improve end-host performance How can we minimize the effect of last mile bottlenecks? Broadband Internet Performance: A View from the Gateway IRTF ANRP, Atlanta, November 2012
  23. http://projectbismark.net http://www.samknows.com Interested in a BISmark router? Interested in contributing? srikanth@gatech.edu Broadband Internet Performance: A View from the Gateway IRTF ANRP, Atlanta, November 2012
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