1 / 28

Things You Can Do in Budapest During Summer Time

Things You Can Do in Budapest During Summer Time. Aleksandar Kuzmanovic Rice University & Ericsson Traffic Lab October 2001. Budapest. Buda-Pest History Architecture Decadency … Ericsson Traffic Lab Unix Young people Security. People. Ericsson Traffic Lab, Budapest Andras Veres

gayora
Download Presentation

Things You Can Do in Budapest During Summer Time

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Things You Can Do in Budapest During Summer Time Aleksandar Kuzmanovic Rice University & Ericsson Traffic Lab October 2001

  2. Budapest • Buda-Pest • History • Architecture • Decadency… • Ericsson Traffic Lab • Unix • Young people • Security Rice University & Ericsson Traffic Lab

  3. People • Ericsson Traffic Lab, Budapest • Andras Veres • EMULab, The University of Melbourne • Attila Pasztor, Darryl Veitch • Budapest University, Department of Physics • Gabor Simon, Gabor Vattay Rice University & Ericsson Traffic Lab

  4. My Goals • Modeling and reality? Rice University & Ericsson Traffic Lab

  5. Active Probing • Internal network inaccessible • Poor understanding of origins of complex network dynamics • Statistics is like the bikini… Goal: Estimate the sample path of cross-traffic Rice University & Ericsson Traffic Lab

  6. Background • Precise measurement infrastructure One way delay (sec) -> Packet departure time (sec) -> Rice University & Ericsson Traffic Lab

  7. Probing Uncertainty Principle • Should not allow queue to empty between probe packets • Small T for accurate measurements • but probe traffic would disturb cross-traffic (and overflow bottleneck buffer!) • Larger T leads to measurement uncertainties • queue could empty between probes Rice University & Ericsson Traffic Lab

  8. Theory • Lindley’s equation • CT information imbedded in delay • Ideal case: minimally backlogging condition [QK99] Rice University & Ericsson Traffic Lab

  9. Design Space • No time synchronization between end points $ 2.000.000.000 • Delay difference • Non-intrusiveness • Stability One way delay (sec) -> Time (sec) -> Rice University & Ericsson Traffic Lab

  10. Probing scheme Rice University & Ericsson Traffic Lab

  11. Aside… • Experiments on LAN • Time-sharing in Linux Inter-arrival time (sec) -> Time (sec) -> Rice University & Ericsson Traffic Lab

  12. Traffic Lab – Experiment Setup • Tcpdump, iperf (HTTP, TCP), sender, receiver… Rice University & Ericsson Traffic Lab

  13. Routes • Tech. University Budapest 6 nec2.ttt.bme.hu (152.66.247.2) 14.980 ms 14.212 ms 14.252 ms • Columbia University, NY 16 bongo.comet.columbia.edu (128.59. 64.210) 150.725 ms * 127.967 ms • University of Melbourne 23 potoroo.ee.mu.OZ.AU (128.250.76.186) 384.271 ms 383.408 ms 382.977 ms • Houston, we have a problem… -> One way delay (sec) -> Time (sec) -> Rice University & Ericsson Traffic Lab

  14. Wide Area vs. Metropolitan Area Network Rice University & Ericsson Traffic Lab

  15. Cross Traffic EstimationSample Path • Differentiate delay, know C • Cross traffic: from: Budapest to: NY iperf - 1 TCP • Probing traffic from: Budapest to: Melbourne Rice University & Ericsson Traffic Lab

  16. Cross Traffic EstimationMoving Average Rice University & Ericsson Traffic Lab

  17. Signs • Delay difference • => two queues • => two cases Rice University & Ericsson Traffic Lab

  18. Wide Area Network revisited • Differentiation btw. primary (256K) & secondary (transatlantic) bottlenecks • Secondary traffic underestimated for Csec./256K Rice University & Ericsson Traffic Lab

  19. Primary & Secondary Bottlenecks • LAN traffic controllable • Separation between primary (256K) & secondary (LAN) cross traffic Rice University & Ericsson Traffic Lab

  20. TCP Cross Traffic • Iperf (number of TCP connections >=3) • => delay decreases yet we see clusters of packet losses (queue size ~ delay~pck. loss?) Rice University & Ericsson Traffic Lab

  21. Role of packet sizes • => change packet size Rice University & Ericsson Traffic Lab

  22. Bit/sec. vs. Packet/sec. • Up: 540 Bytes • Down: 60 Bytes • 540/60 = 9 • 256Kbps*9= 2.3Mbps • UDP: 1500/30=50 • 256K*50= 12.8Mbps - 1.5M*50= 75Mbps Rice University & Ericsson Traffic Lab

  23. Secondary Bottleneck • Difference of CT estimate and tcpdump CT followed by clusters of packet losses Rice University & Ericsson Traffic Lab

  24. Role of TCP • Secondary CT (necessary for losses*) picks up the periodicity of probe traffic! • Through losses • Through delay • When phases match • Long burst of small packets causes losses on secondary bottleneck Rice University & Ericsson Traffic Lab

  25. Ongoing work • Short and long lived TCP connections • Heterogeneous TCP traffic… Rice University & Ericsson Traffic Lab

  26. Conclusions • Scalable,edge-based tool for on-line network analysis, modeling, and measurement • Scheme for estimating sample path of adaptive cross-traffic • Differentiation between primary and secondary bottlenecks: two queue model • Role of TCP (delay variation) and variable packet sizes • Low bit rate denial of service attack? • QoS in access networks (xDSL…) Rice University & Ericsson Traffic Lab

  27. The End Rice University & Ericsson Traffic Lab

  28. One more picture Rice University & Ericsson Traffic Lab

More Related