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CS 5565 Network Architecture and Protocols

CS 5565 Network Architecture and Protocols. Godmar Back. Lecture 5. Announcements. Will hand out Problem Set next week Assignment: Do Ethereal Lab 1 (pg 69 in book) Don’t need to hand it in. Created CS5565 Forum Use this to find a project partner

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CS 5565 Network Architecture and Protocols

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  1. CS 5565Network Architecture and Protocols Godmar Back Lecture 5

  2. Announcements • Will hand out Problem Set next week • Assignment: • Do Ethereal Lab 1 (pg 69 in book) • Don’t need to hand it in. • Created CS5565 Forum • Use this to find a project partner • All 4 projects will be done in groups of up to 2. CS 5565 Spring 2006

  3. Today • Delay in packet-switched networks • Nodal processing delay • Queuing delay • Transmission delay • Propagation delay • End-to-end Delay • traceroute • Structure of Internet CS 5565 Spring 2006

  4. End-to-end vs. nodal delay • Question: in store-and-forward model, end-to-end delay for a message of length L depends on the number/size of packets the message is split into: • Transmission times of packets can be overlayed if multiple packets are part of a message • “Store-and-forward” model applies to packet, not message • Consequence: packetization reduces transmission delay • But you pay a price for header overhead CS 5565 Spring 2006

  5. Latency vs Bandwidth • Latency (Delay)lags Bandwidth[Patterson 2004] • Similar patternin many areas CS 5565 Spring 2006

  6. Bandwidth b Delay d Bandwidth Delay Product • Aka “size of pipe” • Important inprotocol design CS 5565 Spring 2006

  7. 3 probes 3 probes 3 probes traceroute Provides delay measurement from source to router along end-end Internet path towards destination • Problem: • Don’t know which route is taken • How: • Send probes to destination • Tell probes to die off after i hops, i = 1..30 • Ask router to send echo packets if packets dies • Measure RTT CS 5565 Spring 2006

  8. Example Internet delays and routes traceroute: from host in Silicon Valley (keeda.stanford.edu) to host in Frankfurt, Germany (www.titanic-magazin.de) > traceroute www.titanic-magazin.de traceroute to www.titanic-magazin.de (62.75.228.90), 30 hops max, 38 byte packets 1 Gates-rtr.Stanford.EDU (171.64.72.1) 0.523 ms 0.339 ms 0.304 ms 2 bbr2-rtr.Stanford.EDU (171.64.1.161) 0.401 ms 0.346 ms 0.334 ms 3 border2-rtr.Stanford.EDU (171.64.1.148) 4.288 ms 1.070 ms 1.458 ms 4 g1.ba21.b003123-1.sfo01.atlas.cogentco.com (66.250.7.137) 5.231 ms 7.975 ms 9.097 ms 5 g1-1.core02.sfo01.atlas.cogentco.com (66.28.6.13) 11.364 ms 16.192 ms 16.961 ms 6 p14-0.core01.dca01.atlas.cogentco.com (66.28.4.210) 85.497 ms 84.084 ms 80.291 ms 7 p2-0.core01.iad01.atlas.cogentco.com (154.54.2.202) 89.268 ms 88.548 ms 90.046 ms 8 lambdanet.iad01.atlas.cogentco.com (154.54.11.162) 156.812 ms 200.935 ms 157.819 ms 9 LON-2-pos210.uk.lambdanet.net (81.209.156.29) 159.647 ms 159.709 ms 166.504 ms 10 DUS-2-pos700-0.de.lambdanet.net (82.197.136.18) 176.365 ms 163.668 ms 165.177 ms 11 DUS1-5029.de.lambdanet.net (217.71.104.30) 171.229 ms 173.782 ms 171.486 ms 12 titanic.luka.de (62.75.228.90) 172.654 ms 183.307 ms 173.239 ms CS 5565 Spring 2006

  9. “Real” Internet delays and routes traceroute: from host in Silicon Valley (keeda.stanford.edu) to host in Frankfurt, Germany (www.titanic-magazin.de) > traceroute www.titanic-magazin.de traceroute to www.titanic-magazin.de (62.75.228.90), 30 hops max, 38 byte packets 1 Gates-rtr.Stanford.EDU (171.64.72.1) 0.523 ms 0.339 ms 0.304 ms 2 bbr2-rtr.Stanford.EDU (171.64.1.161) 0.401 ms 0.346 ms 0.334 ms 3 border2-rtr.Stanford.EDU (171.64.1.148) 4.288 ms 1.070 ms 1.458 ms 4 g1.ba21.b003123-1.sfo01.atlas.cogentco.com (66.250.7.137) 5.231 ms 7.975 ms 9.097 ms 5 g1-1.core02.sfo01.atlas.cogentco.com (66.28.6.13) 11.364 ms 16.192 ms 16.961 ms 6 p14-0.core01.dca01.atlas.cogentco.com (66.28.4.210) 85.497 ms 84.084 ms 80.291 ms 7 p2-0.core01.iad01.atlas.cogentco.com (154.54.2.202) 89.268 ms 88.548 ms 90.046 ms 8 lambdanet.iad01.atlas.cogentco.com (154.54.11.162) 156.812 ms 200.935 ms 157.819 ms 9 LON-2-pos210.uk.lambdanet.net (81.209.156.29) 159.647 ms 159.709 ms 166.504 ms 10 DUS-2-pos700-0.de.lambdanet.net (82.197.136.18) 176.365 ms 163.668 ms 165.177 ms 11 DUS1-5029.de.lambdanet.net (217.71.104.30) 171.229 ms 173.782 ms 171.486 ms 12 titanic.luka.de (62.75.228.90) 172.654 ms 183.307 ms 173.239 ms CS 5565 Spring 2006

  10. Tier 3 ISP local ISP local ISP local ISP local ISP local ISP local ISP local ISP local ISP NAP Tier-2 ISP Tier-2 ISP Tier 1 ISP Tier 1 ISP Tier 1 ISP Tier-2 ISP Tier-2 ISP Tier-2 ISP Routing across Tiers CS 5565 Spring 2006

  11. Tiers of ISP (cont’d) • Tier 1: usually carriers, own networks/fiber, interconnect with Tier 1 ISPs on reciprocal basis (8 interconnection regions in US), examples: UUnet, Level3, Sprint, CW … • Tier 2: national/regional, connects to Tier 1 (“buys transit”), but peer among each other (AOL, Adelphia, Comcast) - driven by P2P traffic • Tier 3: regional/local providers • Definitions fluent, some are only Tier 1 in some regions • Terms: • POP (point of presence) • NAP (network access point) - public interchanges (Equinix) • Private peering points/links CS 5565 Spring 2006

  12. Before 2000 Crash Source: [Norton 2004] Now LSNSC (large scale network savvy content providers) Changing Landscape of Peering CS 5565 Spring 2006

  13. Summary • Transmission & Propagation Delay • End-to-end delay in packet-switched networks • Traceroute + network diagnostics • Structure of Internet • Bandwidth-delay product • Reminder: please do Lab 1 CS 5565 Spring 2006

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