Broadband Internet Performance: A View from the Gateway

Transcription

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? Important for regulators, consumers, ISPs NoQon of performance is fuzzy What metrics should we measure? How to measure them? Broadband Internet Performance: A View from the Gateway Internet2 Member MeeQng, Fall 2011, Raleigh 2

3 Accurate Measurements are Difficult Home Network: AT&T DSL 6 Mbps Down, 512 Kbps Up Last Mile ISP Network speedtest.net: 4.4 Mbps, 140 Kbps Netalyzr: 4.8 Mbps, 430 Kbps End host measurements are not con/nuous, and affected by confounding factors Broadband Internet Performance: A View from the Gateway Internet2 Member MeeQng, Fall 2011, Raleigh 3

4 The Case For the Gateway Home Network: AT&T DSL 6 Mbps Down, 512 Kbps Up Last Mile ISP Network speedtest.net: 4.4 Mbps, 140 Kbps Netalyzr: 4.8 Mbps, 430 Kbps Gateway: 5.6 Mbps, 460 Kbps Gateway enables periodic measurements, and can account for confounding factors Broadband Internet Performance: A View from the Gateway Internet2 Member MeeQng, Fall 2011, Raleigh 4

5 ContribuQons Study of access networks from the gateway Insight into how to benchmark performance Effect of measurement technique, traffic shaping Effect of access link properqes, home equipment Insight into broadband performance Consistency of performance Loss, ji^er, Qme- of- day effects Broadband Internet Performance: A View from the Gateway Internet2 Member MeeQng, Fall 2011, Raleigh 5

6 The Deployments Last Mile Internet SamKnows/BISmark Nearby Server Breadth: The FCC/SamKnows study 4,000 gateways, 16 ISPs, mulqple service plans Depth: The BISmark study 16 gateways in Atlanta, on- demand measurements DuraQon: Dec 2010 Jan 2011 Broadband Internet Performance: A View from the Gateway Internet2 Member MeeQng, Fall 2011, Raleigh 6

7 Results: Overview Throughput measurement technique depends on usage scenario Traffic shaping is highly variable across users Access link characterisqcs affect performance Modem buffers induce high latency Impact on Web performance Broadband Internet Performance: A View from the Gateway Internet2 Member MeeQng, Fall 2011, Raleigh 7

8 Results: Overview Throughput measurement technique depends on usage scenario Traffic shaping is highly variable across users Access link characterisqcs affect performance Modem buffers induce high latency Impact on Web performance Broadband Internet Performance: A View from the Gateway Internet2 Member MeeQng, Fall 2011, Raleigh 8

9 InterpreQng Throughput Results Different techniques measure different aspects of throughput Broadband Internet Performance: A View from the Gateway Internet2 Member MeeQng, Fall 2011, Raleigh 9

10 Results: Overview Throughput measurement technique depends on usage scenario Traffic shaping is highly variable across users Access link characterisqcs affect performance Modem buffers induce high latency Impact on Web performance Broadband Internet Performance: A View from the Gateway Internet2 Member MeeQng, Fall 2011, Raleigh 10

11 Traffic Shaping: PowerBoost Cable companies adverqse PowerBoost Short bursts of high bandwidth Non- existent in DSL Broadband Internet Performance: A View from the Gateway Internet2 Member MeeQng, Fall 2011, Raleigh 11

12 Traffic Shaping Varies Across Users Short- term throughput significantly different from sustainable throughput Broadband Internet Performance: A View from the Gateway Internet2 Member MeeQng, Fall 2011, Raleigh 12

13 Results: Overview Throughput measurement technique depends on usage scenario Traffic shaping is highly variable across users Access link characterisqcs affect performance Modem buffers induce high latency Impact on Web performance Broadband Internet Performance: A View from the Gateway Internet2 Member MeeQng, Fall 2011, Raleigh 13

14 Latency Measurements Parameter End- to- end Last- mile Under Load What it captures Latency to nearby server Latency to edge of ISP network Buffer delays due to cross traffic Broadband Internet Performance: A View from the Gateway Internet2 Member MeeQng, Fall 2011, Raleigh 14

15 Impact of Last- mile on Latency Cable ISPs DSL ISPs DSL last- mile latencies can be very high Broadband Internet Performance: A View from the Gateway Internet2 Member MeeQng, Fall 2011, Raleigh 15

16 DSL Interleaving Affects Latency Fastpath vs. Interleaved last- mile data path Fastpath sends data in order, can recover from single losses Fastpath is suscepqble to bursty loss Extra Delay Interleaving sends data out- of- order, can recover from bursty loss Broadband Internet Performance: A View from the Gateway Internet2 Member MeeQng, Fall 2011, Raleigh 16

17 Example: Latency- Throughput Tradeoff Throughput (Mbits/s) User 2: high latency, low loss User 1: low latency, high loss Both users have same service plan Interleaving decreases loss, increases latency, improves throughput Latency (ms) Interleaving creates a trade- off between latency and throughput Broadband Internet Performance: A View from the Gateway Internet2 Member MeeQng, Fall 2011, Raleigh 17

18 Results: Overview Throughput measurement technique depends on usage scenario Traffic shaping is highly variable across users Access link characterisqcs affect performance Modem buffers induce high latency Impact on Web performance Broadband Internet Performance: A View from the Gateway Internet2 Member MeeQng, Fall 2011, Raleigh 18

19 Modem Buffers are Too Large 10 seconds! Service plans can interact badly with modem buffers Broadband Internet Performance: A View from the Gateway Internet2 Member MeeQng, Fall 2011, Raleigh 19

20 Results: Overview Throughput measurement technique depends on usage scenario Traffic shaping is highly variable across users Access link characterisqcs affect performance Modem buffers induce high latency Impact on Web performance Broadband Internet Performance: A View from the Gateway Internet2 Member MeeQng, Fall 2011, Raleigh 20

21 Impact on Web Performance Users don t always get benefit of high- end service plans Broadband Internet Performance: A View from the Gateway Internet2 Member MeeQng, Fall 2011, Raleigh 21

22 Bo^lenecks on Performance Web objects are small TCP slow start significantly degrades performance Latencies can be high TCP scales even slower Server side inefficiencies Nearly 1 second to set up TCP transfer (ebay)! No support for persistent connecqons (CNN) Broadband Internet Performance: A View from the Gateway Internet2 Member MeeQng, Fall 2011, Raleigh 22

23 Conclusion The gateway provides unique insight into home network Throughput measurements are affected by measurement technique, shaping Latency is affected by last- mile, buffering Modem buffering is a significant issue ApplicaQon performance is affected by home and server side effects Broadband Internet Performance: A View from the Gateway Internet2 Member MeeQng, Fall 2011, Raleigh 23

24 State of BISmark Deployment Current hardware plaoorm is Netgear WNDR3700v2 Support for TP- Link 1043 and Atom forthcoming Firmware based on OpenWRT Deployment across the world 20+ nodes in US, 10+ in South Africa h_p://projectbismark.net Broadband Internet Performance: A View from the Gateway Internet2 Member MeeQng, Fall 2011, Raleigh 24

25 Future Work Performance monitoring from the edge Effect of peering on performance IPv6 performance Effect of CDN locaqon, traffic engineering on applicaqon performance Understand home network be^er Effect of Wireless Broadband Internet Performance: A View from the Gateway Internet2 Member MeeQng, Fall 2011, Raleigh 25

26 How You Can Help Host BISmark routers Get a high- end router for free! Host measurement servers Geographical diversity is important for reliable measurements bismark- core@projectbismark.net Broadband Internet Performance: A View from the Gateway Internet2 Member MeeQng, Fall 2011, Raleigh 26

27 h_p://projectbismark.net Broadband Internet Performance: A View from the Gateway Internet2 Member MeeQng, Fall 2011, Raleigh 27

28 Previous Studies Measurement from outside Dischinger et al [1] iniqated measurements from wide area server Indirect measurements, not conqnuous Measurements from inside Endhost based measurements Grenouille [2], Netalyzr [3] Can t account for confounding factors [1] Characterizing ResidenQal Broadband Networks IMC 2007 [2] h^p:// [3] h^p://netalyzr.icsi.berkeley.edu Netalyzr: IlluminaQng the Network Edge IMC 2010 Broadband Internet Performance: A View from the Gateway Internet2 Member MeeQng, Fall 2011, Raleigh 28