Wi-SUN Border Router Container

In a Wi-SUN network, the Border Router (BR) is in charge of managing the network (authentication, routing, etc.) and providing internet connectivity to the network.

This Docker image is provided to simplify the deployment and network configuration. It is developed for running on a Raspberry Pi and Raspberry Pi OS (a port of Debian for Raspberry Pi), but it should work on any Linux host.

This implementation relies on an external Silicon Labs EFR32xG12 flashed with a dedicated Wi-SUN RCP (Radio Coprocessor) firmware. To this end, the EFR32 is connected to the host through USB. Using this connection, the Docker image sees the EFR32 device as a serial (UART) connection. This document describes how to set up the system shown below.

The use of a network with IPv6 connectivity is encouraged. If IPv6 is not available, you can use "local" or "site-local" modes (these modes have some pitfalls, see below).

Prerequisites

The document requires the following hardware prerequisites:

• A Raspberry Pi 3 Model B+ or newer
• An SD card of at least 8 GB
• A Silicon Labs WTSK mainboard
• An EFR32MG12 or EFR32FG12 radio board supporting a sub-GHz band

To flash Raspberry Pi OS on the SD card, follow the steps described by the Raspberry Pi Foundation.

It is recommended to update and upgrade your OS. To do so, connect the Raspberry Pi to internet via Ethernet or Wi-Fi and open a console or SSH (Secure Shell) session.

Update the package database:

sudo apt-get update

Upgrade installed packages:

sudo apt-get upgrade

Build the Docker Image

For the time being, the Docker image has to be built. To build and run Docker images, first install the docker application.

sudo apt-get install docker.io

This image is compatible with Docker 20 and newer (Debian 11 or newer).

Make sure that your current user is allowed to run Docker:

sudo usermod -aG docker pi

You have to log out and back in for this to take effect.

You should now be able to clone the repository on your Raspberry Pi:

git clone [email protected]:SiliconLabs/wisun-br-linux-docker.git

Enter the wisun-br-linux-docker directory:

cd wisun-br-linux-docker

Build the image with:

DOCKER_BUILDKIT=1 docker build --build-arg "GIT_DESCRIBE=$(git describe --tag --match v*)" -t wisun-img .

You may save memory by removing the build environment and only keeping the final image:

docker image prune

If you have an IPv6 network, create a macvlan interface to allow the Docker image to access it (replace eth0 by the name of your physical network interface):

sudo docker network create -d macvlan -o parent=eth0 wisun-net

Details on Docker and macvlan can be found here.

Launching the Wi-SUN Docker Image

Before you continue, you have to be aware that by default the image will try to detect existing networks. However this detection may fail (unusual network configuration, DHCP slow to answer, etc...). If no network is detected (and no command line option prevents it), this image advertises a network configuration. It may impact the other hosts on your network. See also Can this image breaks my local network?.

At this stage, you have:

• A Docker image named wisun-img, running the Wi-SUN stack upper-layer and a communication protocol to control an EFR32 running the Wi-SUN RCP image.
• A macvlan interface named wisun-net, allowing a Docker container to access one of the Raspberry Pi IP communication interfaces (by default eth0).

Before connecting the mainboard to your Linux host, start dmesg to monitor new connected devices:

dmesg -w

Next, connect the mainboard with the EFR32 radio board to the Raspberry Pi through USB. Check the name of the new connected device in the dmesg output (by default /dev/ttyACM0). If the device name is different, pass the correct device name with -d (--device) in the following docker run command.

Launch your image using:

docker run -ti --privileged --rm --network=wisun-net --name=wisun-vm wisun-img --flash -

The --flash - option flashes the EFR32 with the default RCP image. More information in the Using the JTAG Link section.

From now on, the Linux Wi-SUN border router should be running and you should be able to connect Wi-SUN nodes to it.

Note that the Docker image accepts several options which you can list with:

docker run -ti --privileged --rm wisun-img --help

You may want to open a shell into the container:

docker exec -ti wisun-vm sh

Advanced users may want to drop the --rm option and work with docker start, docker stop, etc...

Using the JTAG Link

The Docker image is able to use the JTAG link available with the Silicon Labs chips to configure the Wi-SUN parameters, flash the radio board or retrieve chip traces.

You can start the container with --flash - to flash the connected board with the built-in firmware. This firmware works with the EFR23xG12 radio boards supporting a Wi-SUN sub-GHz RF band:

docker run -ti --privileged --rm --network=wisun-net --name=wisun-vm wisun-img --flash -

Replace "-" by another path to flash a custom firmware.

You can also use the JTAG link to retrieve traces from the radio board. You can either pass -T to the docker run command or start the traces afterward with wisun-device-traces command:

docker exec -ti wisun-vm wisun-device-traces

Using DBus interface

From 0.3.0, wsbrd offer a DBus interface to interact with the border router. This image include busctl a generic tools to communicate with DBus. So, user can run commands like:

busctl introspect com.silabs.Wisun.BorderRouter /com/silabs/Wisun/BorderRouter

Obviously, this command only work from the inside the docker. So, from outside the Docker, the full command is:

docker exec wisun-vm busctl introspect com.silabs.Wisun.BorderRouter /com/silabs/Wisun/BorderRouter

The formal specification of the DBus interface is not yet written, however most of the commands are self-described.

Here are a few examples of things you can using DBus.

Retrieve GAKs:

busctl --user get-property com.silabs.Wisun.BorderRouter /com/silabs/Wisun/BorderRouter com.silabs.Wisun.BorderRouter Gaks

Monitor GAKs changes:

busctl --match=type=signal --user monitor com.silabs.Wisun.BorderRouter

Revoke a EUI64:

busctl --user call com.silabs.Wisun.BorderRouter /com/silabs/Wisun/BorderRouter com.silabs.Wisun.BorderRouter RevokeNode ay 8 0x01 0x23 0x34 0x56 0x78 0x9A 0xBC 0xDE

Bugs and Limitations

How to use a local copy of wsbrd sources

During the build, the Dockerfile checks if directory wisun-br-linux exists. In this case, Dockerfile uses this directory instead of cloning the original repository. So, you can do:

git clone ssh://[email protected]/SiliconLabs/wisun-br-linux
DOCKER_BUILDKIT=1 docker build --build-arg "GIT_DESCRIBE=$(git describe --tag --match v*)" -t wisun-img .

Option --ssh default is no more necessary

You have to ensure the version of wisun-br-linux you provide is compatible with this current Docker image.

I want to use this architecture for production

By default, this Docker image uses a method called Neighbor Discovery Protocol Proxy (NDP Proxy). It works with most IPv6 network topologies without touching the network infrastructure. However, it does not scale very well and you may find limitations in corner cases. For production, use the subnet mode (aka Prefix Delegation) or even better use DHCPv6-PD protocol (not presented in this Docker image).

I have no IPv6 network

This project does not aim to provide IPv6 connectivity. If your ISP does not provide IPv6, you can either:

• get equipment providing IPv6 through NAT64 or 6to4
• get equipment advertising a site-local IPv6 prefix (eg. fd01::/64). You can do that using radvd with any standard Linux.

The container does not detect my IPv6 network

The container relies on Router Advertisements. If your network uses DHCPv6, or does not have Router Advertisement for any reason, the container won't detect the network.

Cannot reach (IPv4) Internet from the container

This happens when you use the macvlan driver. It is necessary to get an IP from the DHCP server of the host network. Just add -D when you run the Docker image to run a DHCP client:

docker run -ti --privileged --rm --network=wisun-net --name=wisun-vm wisun-img -D

I have restarted my Docker image and I can't ping my Wi-SUN device anymore

The proxy creates the necessary routes when it receives a Neighbor Solicitation. Your host has probably cached this information. The easiest way to fix that is to flush the neighbor information of your host with:

ip -6 neigh flush dev eth0

Alternatively you can force a neighbor discovery on your Wi-SUN node:

ndisc6 2a01:e35:2435:66a0:202:f7ff:fef0:0 eth0

Wi-SUN can reach an outside network, but can't reach Docker host

It is a limitation of the macvlan interface. This situation is actually not an error — it is the defined behavior of macvtap. Due to the way in which the host's physical Ethernet is attached to the macvtap bridge, traffic into that bridge from the guests that is forwarded to the physical interface cannot be bounced back up to the host's IP stack. Additionally, traffic from the host's IP stack that is sent to the physical interface cannot be bounced back up to the macvtap bridge for forwarding to the guests.

There are several ways to work around the problem. The easiest way probably is to use a secondary physical network interface exclusively for the guest.

dhcpcd --release eth1
docker network create -d macvlan -o parent=eth1 wisun-net
ip link set dev eth1 up
docker run -ti --privileged --rm --network=wisun-net --name=wisun-vm wisun-img

Unable to launch the container on my Windows workstation

This project has not yet been tested on Windows hosts. It seems it should work as soon as you use Windows Subsystem for Linux (WSL2) and the USB-UART of the Wi-SUN BR is handled by WSL2. In other words, you should see /dev/ttyUSB0 on WSL2.

I have reconnected the mainboard and nothing works

The Docker container does not (yet) support device hot-plugging. You have to restart the Docker container if you unplug the mainboard with the EFR32 radio board.

When I try to ping from my Wi-SUN Device, the reply is transmitted after 5s of latency

When using the proxy, it takes a few seconds to establish connection the first time an end device tries to access the outside. The problem is ndppd does not receive locally generated neighbor solicitation (A). The system unlocks when a solicitation comes from outside (B).

    tun0  2 1.806167960 2a01:e35:2435:66a0:20d:6fff:fe20:c096 → 2a00:1450:4007:809::200e ICMPv6 104 Echo (ping) request id=0x0001, seq=0, hop limit=63
    eth0  1 0.000000000 2a01:e35:2435:66a0:20d:6fff:fe20:c096 → 2a00:1450:4007:809::200e ICMPv6 118 Echo (ping) request id=0x0001, seq=0, hop limit=62
    eth0  2 0.007452561 2a00:1450:4007:809::200e → 2a01:e35:2435:66a0:20d:6fff:fe20:c096 ICMPv6 118 Echo (ping) reply id=0x0001, seq=0, hop limit=118 (request in 1)
(A) eth0  3 0.007558306 fe80::42:acff:fe13:2 → ff02::1:ff20:c096 ICMPv6 86 Neighbor Solicitation for 2a01:e35:2435:66a0:20d:6fff:fe20:c096 from 02:42:ac:13:00:02
(A) eth0  4 1.016063581 fe80::42:acff:fe13:2 → ff02::1:ff20:c096 ICMPv6 86 Neighbor Solicitation for 2a01:e35:2435:66a0:20d:6fff:fe20:c096 from 02:42:ac:13:00:02
(A) eth0  5 2.039971376 fe80::42:acff:fe13:2 → ff02::1:ff20:c096 ICMPv6 86 Neighbor Solicitation for 2a01:e35:2435:66a0:20d:6fff:fe20:c096 from 02:42:ac:13:00:02
    eth0  6 3.060057826 2a01:e35:2435:66a0:42:acff:fe13:2 → 2a00:1450:4007:809::200e ICMPv6 166 Destination Unreachable (Address unreachable)
(B) eth0  7 5.043717586 fe80::224:d4ff:fea3:4493 → 2a01:e35:2435:66a0:20d:6fff:fe20:c096 ICMPv6 86 Neighbor Solicitation for 2a01:e35:2435:66a0:20d:6fff:fe20:c096 from 00:24:d4:a3:44:93
    eth0  8 5.043761372 fe80::42:acff:fe13:2 → fe80::224:d4ff:fea3:4493 ICMPv6 174 Redirect
    eth0  9 5.043782371 fe80::42:acff:fe13:2 → ff02::1:ff20:c096 ICMPv6 86 Neighbor Solicitation for 2a01:e35:2435:66a0:20d:6fff:fe20:c096 from 02:42:ac:13:00:02
(B) tun0  3 6.850276506 fe80::10c3:41bf:aa66:69a3 → ff02::1:ff20:c096 ICMPv6 72 Neighbor Solicitation for 2a01:e35:2435:66a0:20d:6fff:fe20:c096 from 00:00:00:00:00:00
    tun0  4 6.870837671 fe80::202:f7ff:fef0:0 → fe80::10c3:41bf:aa66:69a3 ICMPv6 72 Neighbor Advertisement 2a01:e35:2435:66a0:20d:6fff:fe20:c096 (sol) is at 00:02:f7:f0:00:00
    eth0 10 5.067321429 fe80::42:acff:fe13:2 → fe80::224:d4ff:fea3:4493 ICMPv6 86 Neighbor Advertisement 2a01:e35:2435:66a0:20d:6fff:fe20:c096 (rtr, sol) is at 02:42:ac:13:00:02

The subnet mode does not suffer from this limitation.

Can this image break my local network?

When this image starts in site_local mode, it will advertise an IPv6 network configuration. The other hosts on the local network will also receive this configuration and will use it. From here, there are two situations:

1. The hosts already have a valid IPv6 configuration. The new configuration will probably break the current one.

2. The other hosts only use IPv4. IPv4 traffic won't be impacted. However, some DNS records may contain IPv4 and IPv6 fields. In this case, the applications may try to use the new IPv6 configuration. The hosts will forward IPv6 traffic to the Docker image. The image will return an error. Most of the time, the application will fall back to IPv4 and it will work. Else, the application will just stop here with a failure.

If you don't enforce site_local, the image will try to detect existing IPv6 networks. site_local will be started only if no IPv6 network has been detected. The first scenario is unlikely to happen.

If you use site_local mode, we recommend using a dedicated network.

I get Error Connecting DP: cannot read IDR when I try to flash

Check the power supply of the RF board (also check that RF board is correctly present).

On the WTSK mainboard the switch labelled BATT/USB/AEM must be set to AEM.

Further improvements

• Replace radvd with a small RS/RA (Router Solicitation/Router Advertisement) proxy. nd-proxy.c seems to mostly do the job, but:
  1. For an unknown reason, it does not receive RS from tun0 and does not send RA to tun0 (while radvd is able to do that very well).
  2. It is written in C++.
• Provide an example of Prefix Delegation and DHCPv6-PD
• Docker does not yet support --ipam-driver=dhcp --ipam-opt dhcp_interface=eth0