1. IP Performance Measurements using Surveyor Matt Zekauskas matt@advanced.org Guy Almes, Sunil Kalidindi August, 1998 ISMA 98

2. Outline Background Surveyor infrastructure Reporting and analysis Status

3. I: Background Internet topology is increasingly complex Commonly used measurement tools (like ping and traceroute) are inadequate Result: users don’t understand the Internet’s performance and reliability

4. IP Performance Metrics IETF IPPM effort –Framework RFC –One-way delay and packet loss drafts –Others: connectivity, bulk transfer, DV Surveyor: implementation of one-way delay and packet loss metrics

5. Motivation for measuring delay Minimum of delay: transmission/propagation delay Variation of delay: queuing delay Large delay makes sustaining high- bandwidth flows harder Erratic variation in delay makes real- time apps harder

6. Uses Problem determination Engineering (trends, loads) Feedback to advanced applications (e.g., Tele-Immersion, CMU’s Odyssey) Monitor QoS

7. One-way versus round trip Paths are asymmetric Even when paths are symmetric, forward and reverse paths may have radically different performance - asymmetric queuing

8. II. The Surveyor Infrastructure Measurement machines at campuses and at other interesting places along paths (e.g., gigaPoPs, interconnects) GPS to synchronize clocks Centralized database to store measurement data Web based reporting and analysis tools

9. II. Surveyor Infrastructure Measurement machines

10. Measurement Machines Dell 400 MHz Pentium Pro 128 MBytes RAM; 2 GBytes disk BSDI Unix TrueTime GPS card and antenna Network Interface (10/100bT, FDDI) Special driver for the GPS card

11. Measurement Technology Active tests of one-way delay and loss –Measurement daemon –Test packets time-stamped with GPS time –Back-to-back calibration: 95% of measurements ± 50  s –Measurements centrally managed Truer-time daemon to watch clocks

12. Ongoing Tests

13. Ongoing Tests - Delay Type-P –12 byte UDP packets, 40 bytes total –Port “random” per session Scheduled using a Poisson Process –average rate: 2 per second “Mostly” full mesh

14. Ongoing Tests - Routing Traceroute to same sites as One-Way delay Scheduled with Poisson process –average rate: one every 10 minutes

15. Collecting Results

16. Central Database Machine SGI Origin 200 2 processors, 256MB 327GB Fibrechannel-attached RAID for data storage (DataDirect Networks EV-1000)

17. Central Database Machine Collects performance data from the measurement machines [ssh, pull] Stores the data in a home-grown database Serves data and summaries to reporting and analysis tools [http]

18. Current Surveyor Deployment 28 machines, 623 paths –CSG Schools –Tele-Immersion Labs –National Labs –NASA Ames –CA*net2 Ottawa site –Auckland, NZ –…others

19. Surveyor Map (N. America)

20. III. Reporting and analysis tools Web based Tools Daily summary reports Integration with traceroute measurements

21. Daily summary reports Take a 24-hour sample for a given path Divide it into one-minute sub-samples For each one-minute sub-sample: –Minimum delay (blue) –50th percentile (green) –90th percentile (red)

24. Example daily reports Advanced Network & Services and University of Chicago –path is symmetric –asymmetric queuing

29. Examples (continued) Advanced Network & Services and University of Pennsylvania –path asymmetric

32. Examples (continued) CMU to Brown University

35. Examples - Route Change Advanced Network & Services to Penn State University Route change switched providers, and removed one provider from the path

39. Examples - Auckland University of Auckland, NZ to University of Washington, Seattle Asymmetric queuing, congested trans- pacific path

43. IV Status Deployment rate:  1/week Planned: Abilene backbone –probe at each backbone router –experiment with piecewise delay

44. Full Mesh of End-to-end Paths O(N 2 ) paths

45. Paths with Exchange Points O(X 2 +N)

46. Abilene Universities gigaPoPs Router Nodes

47. Near-term improvements Improve measurement software –time stamping in-kernel: to scale without losing accuracy New and improved analyses –real-time display tools –flag interesting paths –trends … –improved data export to other sites

48. Summary One-way Delay and Loss are –practical –useful Surveyor infrastructure growing Now focus on analysis and applications

49. More info Surveyor project info –http://www.advanced.org/surveyor/ –Email: mm-info@advanced.org Access to plots –Email me - matt@advanced.org IETF IPPM WG –http://www.advanced.org/IPPM/