STLTXSingleBurst Ramp-Up Time and Narrow Bursts in TRex v3.4

[Mohsen Meamarian]

Hi everyone,

I have a question regarding the ramp-up time for the STLTXSingleBurst feature in TRex v3.4. Specifically, is it possible to configure the duration to be as short as a microsecond or even a nanosecond? I understand that STLTXSingleBurst takes two arguments—packets per second (pps) and the total number of packets—and that the duration can be calculated from these parameters. However, I'm curious if there's a way to generate very narrow, precise bursts using this feature.

Here’s some additional context on my setup:

• I’m adding streams to a Python list and then sending them using either the Python API or the TRex console.
• I’m also curious about the possibility of achieving this behavior using PCAP files. Is there a way to create narrow bursts using PCAP?

When I run the TRex server (sudo ./t-rex-64 -i) with my current configuration, it takes some time to ramp up throughput from 0 Mpps to 20 Mpps (for 128-byte packet sizes). This behavior leads me to wonder if there's a way to optimize the ramp-up time or configure TRex for faster transitions to maximum throughput.

Here’s my TRex configuration (/etc/trex_cfg.yaml) for reference:

### Config file generated by dpdk_setup_ports.py ###

- version: 2
  interfaces: ['17:00.0', '17:00.1', '98:00.0', '98:00.1']
  c: 24
  #port_bandwidth_gb: 40
  rx_desc: 4096
  tx_desc: 4096
  port_info:
      - dest_mac: 10:70:fd:30:34:51 # MAC OF LOOPBACK TO IT'S DUAL INTERFACE
        src_mac:  10:70:fd:30:34:50
      - dest_mac: 10:70:fd:30:34:50 # MAC OF LOOPBACK TO IT'S DUAL INTERFACE
        src_mac:  10:70:fd:30:34:51

      - dest_mac: 10:70:fd:30:80:d1 # MAC OF LOOPBACK TO IT'S DUAL INTERFACE
        src_mac:  10:70:fd:30:80:d0
      - dest_mac: 10:70:fd:30:80:d0 # MAC OF LOOPBACK TO IT'S DUAL INTERFACE
        src_mac:  10:70:fd:30:80:d1
  platform:
      master_thread_id: 0
      latency_thread_id: 63
      dual_if:
        - socket: 0
          threads: [1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,32,33,34,35,36,37,38,39,40,41,42,43,44,45,46,47]
        - socket: 1
          threads: [16,17,18,19,20,21,22,23,24,25,26,27,28,29,30,31,48,49,50,51,52,53,54,55,56,57,58,59,60,61,62]
  memory:
    traffic_mbuf_64   : 200000


Thanks,
Best