L2 Reflector

NVIDIA DOCA L2 Reflector Application Guide

This document provides an L2 reflector implementation on top of the NVIDIA® BlueField®-3 DPU.

1. Introdution

The BlueField-3 DPU supports high-speed DPA. Data path accelerator allows for accelerated packet processing and manipulation.

DOCA Layer-2 (L2) Reflector uses the DPA engine to intercept network traffic and swap the source and destination MAC addresses of each packet.

2. System Design

The application accepts traffic from specific port given as an argument and leverage the DPA capabilities for accelerated processing.

The following figure shows a view of the high-level components of the application:

3. Application Architecture

DOCA L2 Reflector runs on top of FlexIO SDK to configure the DPA engine.

The FlexIO application consist of two parts:

Host side – responsible for allocating resources and loading them to the DPA
Device side – core processing logic of the application which swaps the MACs on the DPA

For more information, please refer to the NVIDIA DOCA FlexIO SDK Programming Guide.

4. DOCA Libraries and Drivers

This application leverages the following DOCA driver:

FlexIO SDK Library

5. Configuration Flow

This section lists the application's configuration flow which includes different FlexIO functions and wrappers.

Parse application argument.

Initialize arg parser resources and register DOCA general parameters.

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            doca_argp_init();

Register the application's parameters.

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            register_l2_reflector_params();

Parse the arguments.

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            doca_argp_start();

Setup the InfiniBand device.

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            l2_reflector_setup_ibv_device();

Setup the DPA device.

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            l2_reflector_setup_device();

Allocate the device's resources.

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            l2_reflector_allocate_device_resources();

Run initialization function on the device:

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            flexio_process_call();

Create the steering rule.

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            l2_reflector_create_steering_rule();

Start the event handler on the device.

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            flexio_event_handler_run();

Main loop.

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            while (!force_quit)
    sleep(10);

Cleanup the resources.

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            l2_reflector_destroy();

7. Running the Application

Refer to the following documents:
- NVIDIA DOCA Installation Guide for Linux for details on how to install BlueField-related software.
- NVIDIA DOCA Troubleshooting Guide for any issue you may encounter with the installation, compilation, or execution of DOCA applications.
- NVIDIA DOCA Applications Overview for additional compilation instructions and development tips of DOCA applications.
The L2 Reflector binary is located under /opt/mellanox/doca/applications/l2_reflector/bin/l2_reflector. To build all the applications together, run:
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```
            
            cd /opt/mellanox/doca/applications/
meson build
ninja -C build
        
```

To build only the allreduce application:

Edit the following flags in /opt/mellanox/doca/applications/meson_option.txt:
- Set enable_all_applications to false
- Set enable_l2_reflector to true
Run the commands in step 2.

Note:

l2_reflector will be created under ./build/l2_reflector/src/host/.

Application usage:

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            Usage: l2_reflector [DOCA Flags] [Program Flags]
 
DOCA Flags:
  -h, --help                        Print a help synopsis
  -v, --version                     Print program version information
  -l, --log-level                   Set the log level for the program <CRITICAL=20, ERROR=30, WARNING=40, INFO=50, DEBUG=60>
 
Program Flags:
  -d, --device <device name>        Device name

Note:

For additional information on the application, use -h:

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            /opt/mellanox/doca/applications/l2_reflector/bin/l2_reflector -h

CLI example for running the application on BlueField/host:

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            /opt/mellanox/doca/applications/l2_reflector/bin/l2_reflector -d mlx5_0

To run l2_reflector using a JSON file:

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            <application name> --json [json_file]

For example:

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            cd /opt/mellanox/doca/applications/l2_reflector/bin
./l2_reflector –-json ./l2_reflector_params.json

8. Arg Parser DOCA Flags

Refer to NVIDIA DOCA Arg Parser User Guide for more information.

Flag Type	Short Flag	Long Flag/JSON Key	Description	JSON Content
General Flags	`l`	`log-level`	Sets the log level for the application: CRITICAL=20 ERROR=30 WARNING=40 INFO=50 DEBUG=60	Copy Copied! `"log-level": 60`
	`v`	`version`	Print program version information	N/A
	`h`	`help`	Prints a help synopsis	N/A
Program Flags	`d`	`device`	Device name	Copy Copied! `"device": mlx5_0`

9. References

/opt/mellanox/doca/applications/l2_reflector/src/common/l2_reflector_common.h
/opt/mellanox/doca/applications/l2_reflector/src/device/l2_reflector_device.c
/opt/mellanox/doca/applications/l2_reflector/src/host/l2_reflector_core.c
/opt/mellanox/doca/applications/l2_reflector/src/host/l2_reflector_core.h
/opt/mellanox/doca/applications/l2_reflector/src/host/l2_reflector.c
/opt/mellanox/doca/applications/l2_reflector/bin/l2_reflector_params.json

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