How to generate realistic network traffic? Antoine VARET and Nicolas LARRIEU COMPSAC – Vasteras – July the 23rd, 2014 French Civil Aviation University (ENAC) TELECOM Laboratory COMPSAC'14 - N. Larrieu - 1 22 24/07/2014 Why do we need realistic traffic? • To evaluate performances of new network entities – By face them to generated traffic with characteristics as close as possible as the Internet traffic • Lack of adequate tools to generate data flows with “realistic behaviors” at the network or transport level COMPSAC'14 - N. Larrieu - 22-24/07/2014 2 Outline 1. State of the art of traffic generation tools 2. Principles of the SourcesOnOff tool 3. Validation of realism level for traffic generated by our tool COMPSAC'14 - N. Larrieu - 22-24/07/2014 3 Outline 1. State of the art of traffic generation tools 2. Principles of the SourcesOnOff tool 3. Validation of realism level for traffic generated by our tool COMPSAC'14 - N. Larrieu - 22-24/07/2014 4 Different tools for different purposes • Available traffic generators – Network simulators: NS-2 [5], OpNet [6] or OmNet++ [7] On Off sources built-in but inside the simulator – Traffic replay tools: Tcpreplay [8], Harpoon [9] Need first to acquire the traffic trace to replay Mostly packel-level tools, not flow-level tools Retransmit the sniffed packets in the same order, and separated with the same delays as these measured during the capture – Network throughput estimation tools: iperf [10], BWPing [11], Ttcp [12], NetPerf [13], NetPerfMeter [14], Ostinato [15] Interesting throughput statistics Single flow or multiple synchornized flows generation Development of our traffic generator, the SourcesOnOff tool! COMPSAC'14 - N. Larrieu - 22-24/07/2014 5 How to characterize an “Internet-like” traffic profile? • Internet cannot be solely characterized with a small set of parameters (e.g. some mathematical distributions and additional factors) • Not currently one unique mathematical modeling able to embrace the different characteristics and the complexity of the Internet traffic [1] • “Internet” can cover very different profiles, but some common properties can be highlighted: – High variability – Self-similarity COMPSAC'14 - N. Larrieu - 22-24/07/2014 6 Internet traffic characteristics • High variability is characterized by an infinite mathematical variance and means that sudden discontinuous changes can always occur – Some mathematical distributions like Pareto and Weibull are heavy-tailed (i.e. the tail of the distribution is not exponentially bounded) and thus can be used to generate sets of values with high variances and also high- variability [2, 3] • Self-similarity is defined by a long-range dependence characteristic, which means there are bursts of traffic any time over a wide range of time scales. – W. Willinger found in [4] a relation between self-similarity and high variability for Ethernet Local Area Network (LAN) throughputs – The author showed that using ON/OFF sources with heavy-tailed distributions causes the traffic streams to be highly variable and, consequently, the aggregation of these streams to be also self-similar and highly variable COMPSAC'14 - N. Larrieu - 22-24/07/2014 7 ON-OFF sources principles (1) COMPSAC'14 - N. Larrieu - 22-24/07/2014 8 ON-OFF sources principles (2) • Sources parameters (based on random distribution) – Doff distribution: departure time of any source is computed with the departure time (second) of the preceding source plus a random duration. The first source starts at the beginning of the process. – Don distribution: duration times of any source. We generate random values, not for time duration in seconds but for quantity of transmission in bytes (because of TCP congestion control mechanism) • Statistical sources generations – Don and Doff distributions follow statistical processes with heavy-tail characteristic (i.e. Weibull or Pareto laws) – Don and Doff distributions are statistical independent COMPSAC'14 - N. Larrieu - 22-24/07/2014 9 Outline 1. State of the art of traffic generation tools 2. Principles of the SourcesOnOff tool 3. Validation of realism level for traffic generated by our tool COMPSAC'14 - N. Larrieu - 22-24/07/2014 10.