Rocky K. C. Chang, Edmond Chan, Waiting Fok, and Weichao Li. The Hong Kong Polytechnic University Hung hom, Kowloon, Hong Kong

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1 Rocky K. C. Chang, Edmond Chan, Waiting Fok, and Weichao Li The Hong Kong Polytechnic University Hung hom, Kowloon, Hong Kong APRICOT

2 Problem statement Measurement system Measurement methodology Interesting findings Conclusions 2

3 Source: 3

4 Wide area network linking up eight tertiary institutions in HK Managed by Joint Universities Computer Centre (JUCC) Coordinate IT service Provide high-speed optical backbone network and Internet of mutual interest connectivity Bulk tendering and selection of Internet service provider (PCCW Wharf) 4

5 Collect reliable performance data for operation and planning purposes. Justifications for service upgrade Evaluate the fairness of resource sharing among the eight institutions. Achieve some kind of fairness. Improve the quality of network services. Less optimal routes Fault locations 5

6 Problem statement Measurement system Measurement methodology Interesting findings Conclusions 6

7 Operating since 1 Jan 2009 Measurement side OneProbe: provide around-the-clock path-quality monitoring Planetopus: a measurement management platform User side Web-based report on measurement results Ad hoc performance diagnosis 7

8 40+ web servers se elected by the JUCC Planet topus, databa ase, etc HKU CUHK PolyU CityU 8 User side Measurement side BU HKUST LU HKIED

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13 Problem statement Measurement system Measurement methodology Interesting findings Conclusions 13

14 Continuous monitoring Configurable sampling rate and pattern Low overhead User-chosen websites TCP data-path measurement Middlebox friendly Multi-metric measurement Reverse Re-ordering RTT Jitter Reverse Loss OneProbe RTT Forward Loss Forward Re-ordering Round-trip Capacity 14

15 Deploying measurement tasks Monitoring the resources usage Secure measurement data collection Measurement data ma anagement 15

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17 Problem statement Measurement system Measurement methodology Interesting findings Conclusions 17

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19 Strong and diurnal correlation between RTT and reverse-path packet loss 19

20 No correlation between RTT and reverse- path loss 20

21 Good effect of a forward-route change 21

22 The three fault events according to public information: 9 Aug 1:37am(HKT) and 12 hours later EAC 12 Aug 10:50am(HKT) APCN2 17 Aug 2:20pm(HKT) FNAL/RNAL 22

23 Path 9 Aug Australasia - NLA Diurnal RTT burst 1200ms, up to 12 Aug Loss burst 50%, 8 hrs Japan - Nissan Taiwan - TANET US - Citibank Finland - Nokia Korea - KREONET X RTT increase Fw loss increase X X X 12 Aug 17 Aug X Rv Loss 30% RTT burst 1800ms 17 hrs 7 hrs RTT increase 60ms Diurnal Rv loss 10~50%, 22 hrs X X X X Diurnal Rv loss burst - 10~50%, 17+ hrs RTT burst 1800ms, 7hrs Rv Loss 30%, 13 hrs Connectivity Lost 12hrs Rv Loss 50% 1.5 days RTT increase to 400ms 23

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26 Affected by the 9 Aug fault: RTT peaks of 1200ms up to 12 Aug 50%+ burst of losses at 2pm-10pm on 9 Aug PCCW Pacnet TransactSDN(AU) NLA 9 Aug 13:37(HKT) 26

27 Affected by the 12 & 17 Aug faults: Burst of Rv Loss(30%) 3am from 12 Aug 10am to 13 Aug RTT burst of 1800ms on 17 Aug 2-9pm PCCW Equinix NTT(US/JP) OCN(JP) 12 Aug 10:50(HKT) 17 Aug 14:20(HKT) 27

28 Affected by the 12 & 17 Aug faults: RTT increased for 60ms since 12 Aug 15:00 Diurnal Rv Loss (10~50%) in 22 hrs since 12 Aug 16:20 and 17+ hrs since 21:40 17 Aug HKIX ChungHwaTel TANET 12 Aug 10:50(HKT) 17 Aug 14:20(HKT) 28

29 Affected by the 17 Aug fault: RTT burst of 1800ms Reverse-path loss up to 40% From 17 Aug 2pm to 18 Aug 3am PCCW BNA AT& &T 17 Aug 14:20(HKT) 29

30 Affected by the 17 Aug fault: Connectivity lost (OneProbe, TCPTraceroute) From 17 Aug 2pm to 18 Aug 2am Rv Loss burst up to 50% until 20 Aug 4pm PCCW BNA GBLX(US) Nokia(Finland) 17 Aug 14:20(HKT) Connection lost 30

31 Affected by the 17 Aug fault RTT increased from 40ms to 400ms since 17 Aug 14:20 RTT burst of 400ms aro ound 12 Aug 22:00 to 22:30 HARNET ASGC (TW) KREONET 12 Aug 10:50(HKT) 17 Aug 14:20(HKT) 31

32 Deploying and managingg a distributed measurement system is very challenging. A reliable, non-cooperative measurement method A measurement manage ement platform But such a system, if deployed and managed correctly, is very useful. More information obtained from contrasting for performance and fault diagnosis Currently monitoring the impact of switching to a new provider 32

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