1. One-way DelayMeasurement and Accuracy of the Network Time Synchronization Vladimir Smotlacha vs@cesnet.cz TF-NGN, April 2002

2. Measurement of the Accuracy local clock of workstation is synchronized to (far) time server by a method, which is tested workstation is provided by PPS (Pulse Per Second) signal timestamp of each PPS is evaluated sub-second part of timestamp is actual offset of local clock

3. Setup of the Measurement Time Synchronized server -------- network --------- box <--- PPS

4. Current Results

5. Current Results II accuracy of NTP client client: Cesnet server: Heanet

6. OWD Measurement two workstation: traffic generator and receiver clock synchronization –time –frequency clock synchronization accuracy - limiting factor for one- way measurement

7. Organization of Measurement boxes A and B synchronized to NTP server(s) OWD = the difference between both timestamps option: calculation of exact OWD if both A and B are supplied by PPS option: comparison with RIPE TTM results, if RIPE box is available

8. OWD Measurement Setup I + II NTP_ A NTP_B | | Box_A ----- network ----- Box_B NTP_A | Box_A ----- network ----- Box_B ( <-- PPS )

9. OWD Measurement Setup III NTP_A ----- network ----- NTP_B | | institute A netw. institute B netw. | | NTP_A_sec NTP_B_sec | | (PPS --> ) Box_A Box_B ( <-- PPS)

10. Box Specification at least Pentium 120, Pentium II preferred Linux kernel 2.4.16 with nanokernel patch NTP package (4.1.71) Rude/Crude 5.0 or 6.0 PPS available at DCD pin of serial port

11. Plans setup boxes for OWD measurement test commercial systems - NetIQ, IPANEMA compare our method with others available (NetIQ, IPANEMA, RIPE TTM)

12. Participants HEAnet (Ireland) GARR (Italy) FOKUS (Gremany) CESNET (Czech Republic) cooperation with RIPE TTM