Surveyor IP Performance Measurements Matt Zekauskas June, 1999 NLANR/I2 Joint Techs

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

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

Uses Problem determination Engineering (trends, loads) Monitor QoS Feedback to advanced applications (for example, Tele-Immersion)

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

Measurement Machines Dell 400 MHz Pentium Pro 128 MBytes RAM; 8 GBytes disk BSDI Unix TrueTime GPS card and antenna (coax) Network Interface (10/100bT, FDDI, OC3 ATM in alpha) Special driver for the GPS card

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 ± 100 s 10 s soon –Measurements centrally managed Concurrent routing measurements

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

Central Database Machine Collects performance data from the measurement machines [ssh, pull] Stores the data in a home-grown database So far, all measurements taken on-line Serves data and summaries to reporting and analysis tools [http]

Current Surveyor Deployment 50 machines –Universities –Tele-Immersion Labs –National Labs –…others 1883 paths –NASA Ames XP –I2 gigaPoPs (some) –CA*net2 gigaPoPs –APAN sites –Abilene router nodes up with NTP, awaiting GPS

Reporting and analysis tools Web based tools Daily summary reports Integration with route measurements Java applet to dynamically graph almost ready Developing asynchronous notification of anomalies

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)

Lessons so far Routing is asymmetric Even when routing is symmetric, queuing is asymmetric Can detect level 2 changes (SONET failover or ATM) HPC connections do fall back to commodity paths, sometimes frequently or for long periods

Summary One-way Delay and Loss are –practical –useful Surveyor infrastructure growing Dynamic plotting, asynchronous notification coming soon Now focus on analysis and applications

More info Surveyor project info – Access to plots – IETF IPPM WG – My