Table of Contents

1. Introduction

1.1. TRex traffic generator

TRex traffic generator is a tool designed to benchmark platforms using realistic traffic.

One of the tools through which TRex can be learned and tested is a virtual machine instance, fully simulating TRex without the need for any additional hardware.

1.1.1. TRex Virtual Machine

The TRex Virtual Machine is based on Oracle’s Virtual Box freeware.

It is designed to enable TRex newbies to explore this tool without any special resources.

2. Setup and Usage

2.1. Setup

In order to use TRex VM, there are several easy steps to follow:

  1. Download and install Oracle VM Virtual Box Manager (VB download link).
    During installation you will be asked to allow the installation of system devices component interactions. Allow it.

  2. Download the latest TRex VM by clicking on this link. Notice that this is the latest VM image, not the latest TRex version. This can be used for demonstration purposes. After installation, you can upgrade to latest TRex image if needed (Instructions below).

  3. Open Oracle VM Virtual Box application installed at step 1.

  4. Under File tab, select Import Appliance. The following screen will apear:

Figure 1. VM import screen
  1. Browse and select the .ova file you have downloaded at step 2, and click continue.

  2. Click Next, and then make sure that the 'Reinitialize the MAC address of all network cards checkbox is not selected.

  3. Click import and wait for the import process to finish. That’s it! you’re all good and set to go!

2.2. Launching and logging into the machine

First, launch the virtual machine by selecting it in the VM’s menu and hitting Start button.

Figure 2. TRex VM launching screen
Important

You may encounter "VT-x is disabled" error, as shown in the image below.
In that case, please refer to this link and follow the provided steps to overcome this issue.

Figure 3. VT-x disabled possible error message

Once the machine finished booting, login to it using the following credentials:

  • Username: trex

  • Password: trex

Figure 4. TRex VM login
Tip Remote connection to the machine from anywhere in the hosting machine can be set up using the following command:
ssh -p 3022 trex@127.0.0.1

2.3. Running TRex traffic generator

  1. upgrade to the latest trex package see how to upgrade

  2. Change dir to latest version updated for example cd /home/trex/v2.20/. (don’t use the old version in the OVA)

  3. Run your desired TRex command.

Important When launching a TRex command, pay attention to make sure that you are using sudo prefix at the beggining of the command line. + and that you updated to latest v1.62 is very old version

For example, let’s run TRex with DNS traffic. The command is:

[trex@localhost v1.62]$ sudo ./t-rex-64 -f cap2/dns.yaml -d 100 -m 1 --nc
Starting  TRex 1.62 please wait  ...
found configuration file at /etc/trex_cfg.yaml
zmq publisher at: tcp://*:4500

...
1
...

-Per port stats table
      ports |               0 |               1
 -----------------------------------------------------------------------------------------
   opackets |              17 |              17
     obytes |            1241 |            1513
   ipackets |              17 |              17
     ibytes |            1513 |            1241
    ierrors |               0 |               0
    oerrors |               0 |               0
      Tx Bw |     582.35  bps |     709.99  bps

-Global stats enabled
 Cpu Utilization : 0.8  %  0.0 Gb/core
 Platform_factor : 1.0
 Total-Tx        :       1.29 Kbps
 Total-Rx        :       1.29 Kbps
 Total-PPS       :       1.99  pps
 Total-CPS       :       1.00  cps

 Expected-PPS    :       2.00  pps
 Expected-CPS    :       1.00  cps
 Expected-BPS    :       1.30 Kbps

 Active-flows    :        0  Clients :      511   Socket-util : 0.0001 %
 Open-flows      :       17  Servers :      255   Socket :       17 Socket/Clients :  0.0
 drop-rate       :       0.00  bps
 current time    : 18.7 sec
 test duration   : 81.3 sec
1 Output trimmed.

Now, lets review the generated packets as they are observed by our promiscuous interface (interface #2 in the picture at the bottom).
Notice that (depending on your virtual box CPU performance), tcpdump output might be delayed.

[trex@localhost ~]$ sudo tcpdump -i enp0s8
tcpdump: verbose output suppressed, use -v or -vv for full protocol decode
listening on enp0s8, link-type EN10MB (Ethernet), capture size 262144 bytes
09:38:53.953651 IP 16.0.0.2.1024 > 48.0.0.2.domain: 48 A? www.cisco.com. (31)
09:38:53.963969 IP 48.0.0.2.domain > 16.0.0.2.1024: 48* 1/0/0 A 100.100.100.100 (47)
09:38:54.960361 IP 16.0.0.3.1024 > 48.0.0.3.domain: 48 A? www.cisco.com. (31)
09:38:54.970358 IP 48.0.0.3.domain > 16.0.0.3.1024: 48* 1/0/0 A 100.100.100.100 (47)
09:38:55.967200 IP 16.0.0.4.1024 > 48.0.0.4.domain: 48 A? www.cisco.com. (31)
09:38:55.977222 IP 48.0.0.4.domain > 16.0.0.4.1024: 48* 1/0/0 A 100.100.100.100 (47)
09:38:56.975355 IP 16.0.0.5.1024 > 48.0.0.5.domain: 48 A? www.cisco.com. (31)
09:38:56.985379 IP 48.0.0.5.domain > 16.0.0.5.1024: 48* 1/0/0 A 100.100.100.100 (47)
09:38:57.981659 IP 16.0.0.6.1024 > 48.0.0.6.domain: 48 A? www.cisco.com. (31)
09:38:57.992358 IP 48.0.0.6.domain > 16.0.0.6.1024: 48* 1/0/0 A 100.100.100.100 (47)
09:38:58.990979 IP 16.0.0.7.1024 > 48.0.0.7.domain: 48 A? www.cisco.com. (31)
09:38:59.000952 IP 48.0.0.7.domain > 16.0.0.7.1024: 48* 1/0/0 A 100.100.100.100 (47)
09:39:00.009403 IP 16.0.0.8.1024 > 48.0.0.8.domain: 48 A? www.cisco.com. (31)
09:39:00.019456 IP 48.0.0.8.domain > 16.0.0.8.1024: 48* 1/0/0 A 100.100.100.100 (47)
09:39:01.015810 IP 16.0.0.9.1024 > 48.0.0.9.domain: 48 A? www.cisco.com. (31)

Let’s have a look at another example.
We want to generate simple http traffic. The command will look like:

[trex@localhost v1.62]$ sudo ./t-rex-64 -f cap2/http_simple.yaml -d 100 -l 1000 -m 1 --nc
Starting  TRex 1.62 please wait  ...
found configuration file at /etc/trex_cfg.yaml
zmq publisher at: tcp://*:4500

...
1
...

-Per port stats table
      ports |               0 |               1
 -----------------------------------------------------------------------------------------
   opackets |           40983 |           41946
     obytes |         2563951 |         6015664
   ipackets |           41946 |           40983
     ibytes |         6015664 |         2563951
    ierrors |               0 |               0
    oerrors |               0 |               0
      Tx Bw |     520.83 Kbps |       1.27 Mbps

-Global stats enabled
 Cpu Utilization : 3.1  %  0.1 Gb/core
 Platform_factor : 1.0
 Total-Tx        :       1.79 Mbps
 Total-Rx        :       1.79 Mbps
 Total-PPS       :       2.11 Kpps
 Total-CPS       :       2.84  cps

 Expected-PPS    :     102.71  pps
 Expected-CPS    :       2.78  cps
 Expected-BPS    :     764.51 Kbps

 Active-flows    :        0  Clients :      255   Socket-util : 0.0000 %
 Open-flows      :      107  Servers :    65535   Socket :        0 Socket/Clients :  0.0
 drop-rate       :       0.00  bps
 current time    : 39.6 sec
 test duration   : 60.4 sec

-Latency stats enabled
 Cpu Utilization : 1.0 %
 if|   tx_ok , rx_ok  , rx   ,error,    average   ,   max         , Jitter ,  max window
   |         ,        , check,     , latency(usec),latency (usec) ,(usec)  ,
 ----------------------------------------------------------------------------------------
 0 |  39490,  39489,      0,   0,       1276  ,  106714,      91      |  1737  1880
 1 | 39490,   39490,      0,   0,        226  ,  107619,     203      |  1694  1041
1 Output trimmed.
Note See TRex full manual for a complete understading of the tool features and options.

2.4. Updating TRex

See Related manual section

2.5. TRex Live monitoring

Once we have TRex up and running, we can monitor its performance using TRexViewer application (Supported only on Windows OS).

This can be done by following these steps:

  1. Download the latest version of TrexViewer application and install it using this link.

  2. Start the application and fill in the following:

    • Trex ip: 127.0.0.1:4500

  3. Click the play button.

Figure 5. TRex viewer start screen

That’s it!
Now the live data from TRex will be displayed on the screen.

Figure 6. TRex viewer monitor screen
Note Make sure TRex is running, otherwise data will not be available at TRexViewer.

2.6. Architecture and network design

Since no hardware is used, TRex simulates traffic using a virtual internal network, named trex_intnet.

The following figure describes the virtual "wiring" of the virtual machine to support TRex traffic simulation.

Figure 7. TRex virtual connectivity

The VM runs TRex with single client and single server port. The traffic generated by each of those ports is switched over the trex_intnet virtual network and received by the other side.

TRex identifies only the packets which were dedicately sent by one of those traffic ports and receives them on the other port. Hence, packets generated by client port will be received by the server port and vice versa.

Network adapter #4 can be used for capturing all traffic generated by both of TRex’s ports.