TRex Traffic Generator


TRex traffic generator is used for majority of CSIT performance tests. TRex stateless mode is used to measure NDR and PDR throughputs using MLRsearch and to measure maximum transfer rate in MRR tests.

TRex is installed and run on the TG compute node. The typical procedure is:

  • TRex configuration is set in its configuration file

    $ sudo -E -S sh -c 'cat << EOF > /etc/trex_cfg.yaml
    - version: 2
      c: 15
      limit_memory: 8192
      interfaces: ["${pci1}","${pci2}"]
        - dest_mac: [${dest_mac1}]
          src_mac: [${src_mac1}]
        - dest_mac: [${dest_mac2}]
          src_mac: [${src_mac2}]
      platform :
        master_thread_id: 0
        latency_thread_id: 16
            - socket: 0
              threads: [1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15]
  • TRex is started in the interactive mode as a background service

    $ sh -c 'cd <t-rex-install-dir>/scripts/ && \
      sudo nohup ./t-rex-64 -i --prefix $(hostname) --hdrh --no-scapy-server \
      > /tmp/trex.log 2>&1 &' > /dev/null
  • There are traffic streams dynamically prepared for each test, based on traffic profiles. The traffic is sent and the statistics obtained using API trex.stl.api.STLClient.

Measuring Packet Loss

Following sequence is followed to measure packet loss:

  • Create an instance of STLClient.

  • Connect to the client.

  • Add all streams.

  • Clear statistics.

  • Send the traffic for defined time.

  • Get the statistics.

If there is a warm-up phase required, the traffic is sent also before test and the statistics are ignored.

Measuring Latency

If measurement of latency is requested, two more packet streams are created (one for each direction) with TRex flow_stats parameter set to STLFlowLatencyStats. In that case, returned statistics will also include min/avg/max latency values and encoded HDRHistogram data.