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DIMES Measurements

DIMES Measurements. Topics. Description of the measurement module’s structure How it’s activated What the output looks like Measurement algorithm Hop alternatives Protocols Glitches and observations Writing measurements for DIMES. Structure of the measurement module.

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DIMES Measurements

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  1. DIMES Measurements

  2. Topics • Description of the measurement module’s structure • How it’s activated • What the output looks like • Measurement algorithm • Hop alternatives • Protocols • Glitches and observations • Writing measurements for DIMES

  3. Structure of the measurement module • Uniform API (Measurements) • Uniform activation • Uniform result export – should be adapted to new types of measurements • Native implementation of actual measurement, due to Java limitations

  4. execute execute Ping Operation Traceroute Operation Measurements executeMTR(HostIP, MeasurementType, Protocol,PingNum,InitialPort) Measurements DLL

  5. Result File <OperationResult> <ExID>DimesExperiment</ExID> <ScriptID>AllIPs_5841</ScriptID> <Priority>NORMAL</Priority> <StartTime>2005-05-16 13:01:21.995</StartTime> <LocalStartTime>2005-05-16 15:01:21</LocalStartTime> <CommandType>TRACEROUTE</CommandType> <Protocol>UDP</Protocol> <SourceName>nolly-pc</SourceName> <SourceIP>132.66.50.231</SourceIP> <DestName>207.228.245.59</DestName> <DestIP>207.228.245.59</DestIP> <DestAddress>807078631</DestAddress> <NumOfTrials>4</NumOfTrials> <Success>true</Success> <reachedDest>true</reachedDest> <Exceptions></Exceptions> <RawDetails> … </RawDetails> </OperationResult>

  6. <RawDetails> <Detail> <sequence>1</sequence> <hopAddress>2076037149</hopAddress> <hopAddressStr>132.66.48.1</hopAddressStr> <hopNameStr>cisco.eng.tau.ac.il</hopNameStr> <lostNum>0</lostNum> <bestTime>0</bestTime> <worstTime>0</worstTime> <avgTime>0</avgTime> <exception></exception> </Detail> … <Detail> <sequence>16</sequence> <hopAddress>807078792</hopAddress> <hopAddressStr>207.228.244.150</hopAddressStr> <hopNameStr>207.228.244.150</hopNameStr> <lostNum>0</lostNum> <bestTime>161</bestTime> <worstTime>164</worstTime> <avgTime>163</avgTime> <exception></exception> </Detail> </RawDetails> Hop Details

  7. MTR - Traceroute and Ping • Same algorithm for both measurements • 4 traces in 1 measurement (was 10) • 2 possible protocols – ICMP, UDP • Increasing UDP ports • Delay between packet sending

  8. Measurements Algorithm While (numPing < maxNumPing) If (time to send next packet) If (current TTL > max TTL) or (current TTL > min responsive TTL) return send packet (current TTL, current port num) if (traceroute) ++ current TTL wait for packet for short period and process if finished a trace ++ numPing reset TTL ++ port num

  9. Hop Alternatives Separate traces in a single measurement Different IPs emerge for the same hop Possible reasons: • Different routes • route flapping • Load balancing • Same route, different hop IP • Router interfaces

  10. <Detail> <sequence>12</sequence> <hopAddress>71596326</hopAddress> <hopAddressStr>4.68.121.38</hopAddressStr> <hopNameStr>ge-1-2-52.car2.Washington1.Level3.net</hopNameStr> <lostNum>0</lostNum> <bestTime>159</bestTime> <worstTime>164</worstTime> <avgTime>162</avgTime> <exception></exception> <Alternatives> <Detail> <sequence>12</sequence> <hopAddress>71596390</hopAddress> <hopAddressStr>4.68.121.102</hopAddressStr> <hopNameStr>ge-1-2- 54.car2.Washington1.Level3.net</hopNameStr> <lostNum>0</lostNum> <bestTime>159</bestTime> <worstTime>159</worstTime> <avgTime>159</avgTime> <exception>null</exception> </Detail> </Alternatives> </Detail> Result File RevisitedHop Alternatives

  11. Differences in packet handling policies – noisy results • Block (ignore) • Accumulating/batch block (reply to 5 packets in every 10) • Delay block (reply to a packet, then wait a fixed delay in which you block) • Several echo replies to a single request

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