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      How to Use Burst Mode for Ethernet Traffic Generation

      What is Burst Mode?

      Burst mode is a feature that is commonly used to simulate “bursty” traffic loads on a network device.

      This mode is used as a more realistic method of testing network loads than a constant bandwidth, because Ethernet traffic is typically “bursty” by nature.

      Configuration Settings: (using the MPA's WebUI)

      1. Select the Ethernet's Traffic tab.
      2. Click the edit icon  for the test stream(s) to configure their Traffic Stream Profile(s).
      3. Select either Constant L1 Bandwidth % or Constant L1 Mbps from the Rate menu in the Traffic Schedule area. 
      4. Then click on the Burst Size setting and the number of packets to burst.
        1. This is sometimes also referred to as the Burst Width.

      Notes: 

      • The Burst size is the number of packets to be transmitted at 100% BW during each burst, including the minimum Inter-Packet Gap (IPG) allowed between each packet.
      • For example, a 1GigE stream configured for 100% BW with a Frame Size of 128 bytes has a maximum Frame Rate of about 844594 packets per second.
      • When the Burst Size is set to 844594, this generates a burst of exactly 844594 packets, at 100% bandwidth for a full 1 second, with the minimum Inter-Packet Gap between each packet, regardless of the Rate setting. 
      • A Burst Size of 1/2 the max (422297 for this example) would generate 100% bandwidth for 1/2 a second, then the amount of “Off” time (aka idle period) would depend on the Rate setting. 
      • The Rate is the “ratio of time” that packets are “On” for (at 100% BW), versus “Off” for (at 0% BW).
      • So if the Rate is set to 50%, then an alternating burst of 100% BW would last for the same amount of time as each idle period of 0% BW. 
      • The greater the Rate, the shorter the “Off” time. The lower the Rate, the greater the “Off” time.

       

      How to test constant Burst mode:

      1. Verify you have round-trip continuity by temporarily enabling the test stream(s), and verify that both the TX and RX Packet counts are increasing.
      2. Turn OFF the test stream(s), and press the port's Restart buttons on both the MPA and the device under test (DUT) to clear any previous packet count history. 
      3. Next, back turn ON the test stream(s) that are configured for Burst Mode, as described above.
      4. Monitor the network DUT for anomalies, as the bursts of generated packets are received, until the test is stopped.
      5. Turn OFF the test streams, and verify that the DUT’s RX Packet count matches the MPA’s TX Packet count.

       

      How to test single Burst mode:

      • The user also has the ability to transmit a single burst using the “Send Burst” button to the right of the stream's On/Off toggle switch.
      • This will generate one-time burst, each time this button is pressed, for the exact number of packets that the stream’s Burst Size setting is configured for (ranging from 1 to 2,000,000,000 packets per burst).