1. ADVANCED NETWORK & SERVICES, INC. Surveyor Design and Results Bill Cerveny and Sunil Kalidindi Advanced Network & Services

2. ADVANCED NETWORK & SERVICES, INC. Surveyor Measurement Infrastructure

3. ADVANCED NETWORK & SERVICES, INC. Participants

4. ADVANCED NETWORK & SERVICES, INC. Implementation Decisions

5. ADVANCED NETWORK & SERVICES, INC. Time Synchronization Essential to one way delay measurements Choices considered –NTP –Radio time synchronization –Global Positioning System (GPS) –Dial-up time synchronization software and services GPS was chosen for its high accuracy (within 10 microseconds in actual usage)

6. ADVANCED NETWORK & SERVICES, INC. Time Synchronization (con’t) GPS Tradeoffs –GPS time precision hardware uncommon and costly –Requires rooftop antennas –RF interference problems Interference resistant antennas being investigated

7. ADVANCED NETWORK & SERVICES, INC. Measurement Frequency Two measurements per second per path: –172,000 measurements per day per path –1,797 paths –2.5 GB of measurement data across all paths daily Strains measurement infrastructure: measurement machines, database, network Comparison with RIPE infrastructure suggests less frequent measurements may be sufficient

8. ADVANCED NETWORK & SERVICES, INC. Impact of Other Measurements Key placement of machines in Internet infrastructure make performing additional measurements attractive Accuracy of core one-way delay and packet loss must not be impacted due to other measurements We are performing “traceroutes” to all paths without impacting accuracy

9. ADVANCED NETWORK & SERVICES, INC. Recent Results

10. ADVANCED NETWORK & SERVICES, INC. Loss over transatlantic paths 16 paths measured between Nov ‘98 and April ‘99 Loss averaged out over 5 months looks OK on all the paths (around 1%). Typically, paths are congested only during certain times of the day. Considering loss over the entire day, averaging hides the periods of congestion

11. ADVANCED NETWORK & SERVICES, INC. Worst Hour Packet Loss For each path, for each day consider only the one-hour period when the loss is the worst. Take average daily worst-hour packet loss over the month for each path and then averaged over all paths: –Nov ‘984.5% –Dec ‘982.8% –Jan ‘994.4% –Feb ‘998.0% –Mar ‘995.0%

12. ADVANCED NETWORK & SERVICES, INC. Which paths are congested? For purposes of this analysis, a path is considered “congested” on a given day if the worst-hour packet loss > 5% Over a 5-month period between Nov ‘98 and March ‘99, we classified the paths based on how many days they were “congested” during the day’s worst hour.

13. ADVANCED NETWORK & SERVICES, INC. Which paths are congested? GOOD - 7 (congested < 25% of the days) BAD - 8 (>25% but <50% of days) UGLY - 1 (congested > 50% of days)