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University of Virginia Computer Science CS150: Computer Science, Fall 2005 |
(none) 2 November 2005 |
Bandwidth: how much data can be transmitted per unit time (bits per second)
You can think of latency as the length of the pipe, and bandwidth as the width of the pipe.
How can we improve latency of a network?
How can we improve bandwidth of a network?
What things you do on the Internet would be better if latency was lower (faster) and bandwidth was reduced?
What things you do on the Internet would be better if latency was higher (slower) and bandwidth was increased?
] tracert www.virginia.edu Tracing route to www.virginia.edu [128.143.22.36] over a maximum of 30 hops: 1 <10 ms <10 ms <10 ms router137.cs.Virginia.EDU [128.143.137.1] 2 <10 ms <10 ms <10 ms www.Virginia.EDU [128.143.22.36] Trace complete. ] tracert www.jmu.edu Tracing route to finch.jmu.edu [134.126.10.60] over a maximum of 30 hops: 1 <10 ms <10 ms <10 ms router137.cs.Virginia.EDU [128.143.137.1] 2 <10 ms <10 ms <10 ms carruthers-6509a-x.misc.Virginia.EDU [128.143.222.46] 3 <10 ms <10 ms <10 ms uva-internet.acc.Virginia.EDU [128.143.222.93] 4 70 ms 40 ms 60 ms nwv-wash-uva.misc.Virginia.EDU [192.35.48.46] 5 50 ms 30 ms 70 ms 65.162.89.38 6 50 ms 30 ms 90 ms JamesMadisonU-ROA.networkvirginia.net [204.95.121.114] 7 50 ms 40 ms 80 ms wilson-core.jmu.edu [134.126.2.6] 8 80 ms 61 ms 110 ms finch.jmu.edu [134.126.10.60] Trace complete. ] tracert www.fsu.edu Tracing route to www.fsu.edu [128.186.6.14] over a maximum of 30 hops: 1 <10 ms <10 ms <10 ms router137.cs.Virginia.EDU [128.143.137.1] 2 <10 ms <10 ms <10 ms carruthers-6509a-x.misc.Virginia.EDU [128.143.222.46] 3 <10 ms <10 ms <10 ms uva-internet.acc.Virginia.EDU [128.143.222.93] 4 <10 ms <10 ms 10 ms abilene-uva.misc.Virginia.EDU [192.35.48.42] 5 <10 ms 10 ms <10 ms 192.70.138.22 6 10 ms 20 ms 20 ms atla-washng.abilene.ucaid.edu [198.32.8.65] 7 * * * Request timed out. 8 20 ms 30 ms 20 ms sox2fsu-a5002.c7507.fsu.edu [192.80.53.114] 9 20 ms 30 ms 30 ms vlan916.6509.bfs.fsu.edu [128.186.250.17] 10 20 ms 30 ms 20 ms www.fsu.edu [128.186.6.14] Trace complete. ] tracert www.govt.nz Tracing route to www.webportal.govt.nz [202.27.77.188] over a maximum of 30 hops: 1 <10 ms <10 ms <10 ms router137.cs.Virginia.EDU [128.143.137.1] 2 <10 ms <10 ms <10 ms carruthers-6509a-x.misc.Virginia.EDU [128.143.222.46] 3 <10 ms <10 ms <10 ms uva-internet.acc.Virginia.EDU [128.143.222.93] 4 400 ms 351 ms 381 ms nwv-wash-uva.misc.Virginia.EDU [192.35.48.46] 5 271 ms 280 ms 221 ms 65.162.89.38 6 301 ms 350 ms 291 ms sl-gw20-rly-2-2.sprintlink.net [160.81.255.1] 7 220 ms 221 ms 150 ms sl-bb20-rly-3-2.sprintlink.net [144.232.14.29] 8 180 ms 311 ms 420 ms sl-bb20-sj-5-3.sprintlink.net [144.232.9.218] 9 230 ms 321 ms 350 ms sl-st20-pa-15-1.sprintlink.net [144.232.20.42] 10 171 ms 120 ms 330 ms sl-newzeal-1-0.sprintlink.net [144.223.243.18] 11 441 ms 410 ms 411 ms p4-0.akbr2.global-gateway.net.nz [202.50.116.177] 12 401 ms 401 ms 340 ms f2-0-0.akbr1.global-gateway.net.nz [202.50.116.166] 13 421 ms 431 ms 400 ms oil-dsl-int.akbr1.global-gateway.net.nz [202.50.119.158] 14 470 ms 481 ms 451 ms 202.175.136.129 15 601 ms 681 ms 521 ms 192.203.216.21 16 490 ms 451 ms 371 ms 192.203.216.22 17 * * * Request timed out. ... 30 * * * Request timed out. Trace complete.Tallahassee, Florida is about 1200 km from Charlottesville, VA and it takes about 20 milliseconds for data to travel from my office to www.fsu.edu. The fastest data can move is the speed of light (300 000 000 meters per second). If data on the Internet travelled at the speed of light, it would take 3.7 milliseconds. How much opportunity is there to realistically improve the latency of the Internet?
Is data moving at a faster average speed between my office and Tallahassee or my office and New Zealand?
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CS 150: Computer Science University of Virginia |
evans@virginia.edu Using these Materials |