[dts] [PATCH for-next v3 6/7] doc: Add T-Rex section to documentation

[Patrick MacArthur <pmacarth@iol.unh.edu>]

Explain how DTS expects T-Rex to be set up; in particular, explain that
T-Rex should be started in Layer 2 mode as opposed to Layer 3 mode, to
avoid the need to resolve the destination MAC address.

Signed-off-by: Patrick MacArthur <pmacarth@iol.unh.edu>
---
 doc/dts_gsg/index.rst                         |  1 +
 doc/dts_gsg/trex.rst                          | 27 +++++++++++++++++++++++++++
 test_plans/nic_single_core_perf_test_plan.rst |  2 ++
 3 files changed, 30 insertions(+)
 create mode 100644 doc/dts_gsg/trex.rst

diff --git a/doc/dts_gsg/index.rst b/doc/dts_gsg/index.rst
index fbd16dc053b0..d21e3343fa14 100644
--- a/doc/dts_gsg/index.rst
+++ b/doc/dts_gsg/index.rst
@@ -42,3 +42,4 @@ Getting Started Guide
     virtualization
     scenario
     multiple_vm
+    trex
diff --git a/doc/dts_gsg/trex.rst b/doc/dts_gsg/trex.rst
new file mode 100644
index 000000000000..ab6dfa520feb
--- /dev/null
+++ b/doc/dts_gsg/trex.rst
@@ -0,0 +1,27 @@
+Configuring T-Rex for DPDK Test Suite
+=====================================
+
+DPDK can utilize T-Rex as a traffic generator in stateless Layer 2 mode.
+This is supported for the ``nic_single_core_perf`` test but may be usable
+by other tests in the future.
+
+An example T-Rex configuration that accomplishes this is shown as follows:
+
+.. code-block:: console
+
+  - port_limit: 2
+    version: 2
+    interfaces: ["03:00.0", "03:00.1"]
+    port_info:
+            - src_mac: "aa:bb:cc:dd:ee:ff"
+              dest_mac: "ff:ee:dd:cc:bb:aa"
+            - src_mac: "ff:ee:dd:cc:bb:aa"
+              dest_mac: "aa:bb:cc:dd:ee:ff"
+
+DTS may use a standalone T-Rex instance, or can be configured to start T-Rex
+itself using the settings in ``pktgen.conf``.
+
+To read more about T-Rex stateless mode, read the
+`T-Rex stateless support guide`_.
+
+:: _T-Rex stateless support guide: https://trex-tgn.cisco.com/trex/doc/trex_stateless.html
diff --git a/test_plans/nic_single_core_perf_test_plan.rst b/test_plans/nic_single_core_perf_test_plan.rst
index 912c60d57097..428d5db29fbf 100644
--- a/test_plans/nic_single_core_perf_test_plan.rst
+++ b/test_plans/nic_single_core_perf_test_plan.rst
@@ -49,6 +49,8 @@ Prerequisites
     dts (next branch): git clone http://dpdk.org/git/tools/dts, 
                        then "git checkout next" 
     Trex code: http://trex-tgn.cisco.com/trex/release/v2.26.tar.gz 
+               (to be run in stateless Layer 2 mode, see section in
+                Getting Started Guide for more details)
     python-prettytable: 
         apt install python-prettytable (for ubuntu os) 
         or dnf install python-prettytable (for fedora os). 
-- 
2.14.1