Jump to main content

##

# 1.4 TCP/IP Berkeley UDP Relay

The Berkeley UDP Relay application demonstrates the use of multiple sockets for sending and receiving UDP packets. There are three different sub-functions for this application:

- UDP Relay, which accepts UDP packets on one socket and sends the packets out on a different socket.
- UDP Relay Client, which generates UDP traffic that is compatible with the UDP Relay Server.
- UDP Relay Server, which receives and checks traffic for a packet count and reports any packet drop.

## Description

The TCP/IP Berkeley UDP Relay application is based on MPLAB® Harmony 3 TCP/IP Stack.

The Harmony TCP/IP stack is a collection of different network protocols.

The source files of Harmony 3 TCP/IP stack is available here.

The demo is created with MPLAB X IDE and MCC plugin.

MCC Project Graph - TCP/IP Berkeley UDP Relay

The following Project Graph shows the Harmony components included in the TCP/IP Berkeley UDP Relay demo application.

Figure 1-10.Project Graph

TCP sockets calculate the ISN using the wolfSSL crypto library.

FreeRTOS component is required for RTOS application. For bare-metal (non-RTOS) FreeRTOS component should not be selected.

TCP/IP Configuration - TCP/IP Berkeley UDP Relay

The TCP/IP modules enabled for the demo is shown in the TCP/IP Configuration Overview.

More details of TCP/IP Configuration plugin is available here.

Figure 1-11.SAM9X60-Curiosity

The Application Layer modules enabled in the demo are as follows:

- Application Layer Modules
  - Announce to discover the Microchip devices within a local network.
  - Berkeley API provides the Berkeley_Socket_Distribution (BSD) wrapper to the native Harmony TCP/IP Stack APIs.
  - DHCP Client to discover the IPv4 address from the nearest DHCP Server.
  - DNS Client provides DNS resolution capabilities to the stack.

## Downloading and Building the application

To clone or download this application from Github, go to the main page of this repository and then click Clone button to clone this repository or download as zip file.

This content can also be downloaded using content manager by following these instructions.

Path of the application within the repository is apps\berkeley_udp_relay\firmware.

To build the application, refer to the following list of demo configurations and open the project using MPLAB X IDE.

Table 1-4.Demo Configurations
Project Name | Target Device | Development Board | Description
--- | --- | --- | ---
sam_9x60_curiosity.X | SAM9X60D1G | SAM9X60-Curiosity | TCP/IP Berkeley UDP Relay with an on-board KSZ8081 PHY - Bare Metal
sam_9x60_curiosity_freertos.X | SAM9X60D1G | SAM9X60-Curiosity | TCP/IP Berkeley UDP Relay with an on-board KSZ8081 PHY - FreeRTOS

## Hardware Setup - SAM9X60-Curiosity

The target board for running the application is SAM9X60-Curiosity.

This section provides essential hardware configuration of this target board to run TCP/IP applications.

Figure 1-12.SAM9X60-Curiosity Development Board

Board Setup

To set up the hardware, refer to the section Board Setup in SAM9X60-Curiosity User's Guide.

- Connect the micro-USB cable from the computer to connector J1 (USB_A port) on the SAM9X60-Curiosity Development Board.
- Connect a USB-UART converter from the computer to J11 (UART DEBUG port) on the SAM9X60-Curiosity Development Board.
- Connect a debugger/programmer(like MPLAB® ICD) from the computer to the J12 (JTAG connector) on the SAM9X60-Curiosity Development Board.
- Establish a connection between the router/switch with the SAM9X60-Curiosity Development Board through the RJ45 connector.

## Setting up at91bootstrap loader

To load the application binary onto the target device, we need to use at91bootstrap loader.

Refer to the at91bootstrap loader documentation for details on how to configure and run/debug the application using MPLABX and booting application using an SD Card.

## Running the Application

1. Open a terminal application on the host computer (like Hyper-terminal or Tera Term).
2. Configure the terminal application for serial port connected to USB-UART converter.
3. Set baud rate as 115200 in the terminal application.
4. Build and download the application project on the target board.
5. Verify the TCP/IP Stack initialization console messages.

Console Start up

If DHCP client is enabled in the demonstration, wait for the DHCP server to assign an IP address for the development board.

This will be printed on the console. Otherwise, the default static IP address will be assigned to the board.

By entering the command netinfo, the response is obtained as shown above.

Berkeley UDP Relay Test

For UDP Relay test, a relay host (UDP Server) application is required to run on the host computer.

Application commands for this demo are:

- current - Displays the current configuration.
- start - Starts the packet relay service.
- stop - Stops the packet relay service.
- relayhost < host name > - Sets the host to which packets are to be relayed.
- relayport < port number > - Sets the port to which packets are to be relayed.
- ipv4port < port number > - Sets the IPv4 port that the relay server will listen to for packets to relay.
- ipv6port < port number > - Sets the IPv6 port that the relay server will listen to for packets to relay.
- relayclienthost < host name > - Sets the host to which packets are to be sent.
- relayclientiter < number > - The number of packets to generate.
- relayclientstart - Starts the relay client. This command must be used after the start command.

To test the UDP packet relay with IPv4, send the following commands:

- relayclienthost < ip address of the relay client >
- relayclientiter < number of packets to relay >
- relayhost < ip address of the host to which packets are to be relayed >
- relayport < port number to which packets are to be relayed >
- ipv4port < port number to which the relay server listens to, for packets to relay >
- current
- start
- relayclientstart

Output - This will relay the UDP packet from the host address, set using the relayclienthost command, to the destination address set by the command relayhost.

The relay packet will be received at the port set by command relayport.

After start command and the first packet is received by either the relay or the relay server, periodic updates will be sent to the console with information about the number of packets and bytes received.