Echo Server

Overview

The echo-server sample application for Zephyr implements a UDP/TCP server that complements the echo-client sample application: the echo-server listens for incoming IPv4 or IPv6 packets (sent by the echo client) and simply sends them back.

The source code for this sample application can be found at: samples/net/echo_server.

Requirements

Building and Running

There are multiple ways to use this application. One of the most common usage scenario is to run echo-server application inside QEMU. This is described in Networking with QEMU.

There are configuration files for different boards and setups in the echo-server directory:

  • prj.conf Generic config file, normally you should use this.
  • overlay-frdm_k64f_mcr20a.conf This overlay config enables support for IEEE 802.15.4 mcr20a and frdm_k64f
  • overlay-ot.conf This overlay config enables support for OpenThread.
  • overlay-802154.conf This overlay config enables support for native IEEE 802.15.4 connectivity. Note, that by default IEEE 802.15.4 L2 uses unacknowledged communication. To improve connection reliability, acknowledgments can be enabled with shell command: ieee802154 ack set.
  • overlay-enc28j60.conf This overlay config enables support for enc28j60 ethernet board. This add-on board can be used for example with Arduino 101 board.
  • overlay-cc2520.conf This overlay config enables support for IEEE 802.15.4 cc2520 chip.
  • overlay-bt.conf This overlay config enables support for Bluetooth IPSP connectivity.
  • overlay-qemu_802154.conf This overlay config enables support for two QEMU’s when simulating IEEE 802.15.4 network that are connected together.
  • overlay-tls.conf This overlay config enables support for TLS.
  • overlay-netusb.conf This overlay config enables support for Ethernet over USB setup with supported boards. The setup is described in USB Device Networking

Build echo-server sample application like this:

# On Linux/macOS
cd $ZEPHYR_BASE/samples/net/echo_server
mkdir build && cd build
# On Windows
cd %ZEPHYR_BASE%\samples\net\echo_server
mkdir build & cd build
cmake -GNinja -DBOARD=<board to use> -DCONF_FILE=<config file to use> ..
ninja

Example building for the FRDM-K64F with TI CC2520 support:

cd $ZEPHYR_BASE/samples/net/echo_server
mkdir build && cd build
cmake -GNinja -DBOARD=frdm_k64f -DCONF_FILE="prj.conf overlay-frdm_k64f_cc2520.conf" ..
ninja run

Make can select the default configuration file based on the BOARD you’ve specified automatically so you might not always need to mention it.

Running echo-client in Linux Host

There is one useful testing scenario that can be used with Linux host. Here echo-server is run in QEMU and echo-client is run in Linux host.

To use QEMU for testing, follow the Networking with QEMU guide.

Run echo-server application in QEMU:

cd $ZEPHYR_BASE/samples/net/echo_server
mkdir build && cd build
cmake -GNinja -DBOARD=qemu_x86 ..
ninja run

In a terminal window:

$ sudo ./echo-client -i tap0 2001:db8::1

Note that echo-server must be running in QEMU before you start the echo-client application in host terminal window.