Pelion Border Router

Pelion Border router is a Pelion Device Management enabled border router implementation that provides the Wi-SUN border router logic.

A border router is a network gateway between a wireless Wi-SUN mesh network and a backhaul network. It controls and relays traffic between the two networks. In a typical setup, a Wi-SUN border router is connected to another router in the backhaul network (over Ethernet) which in turn forwards traffic to and from the internet or a private company LAN.

The code layout is organized like this:

configs/                  Contains Mbed TLS configs and Wisun Certificates
bootloader/               Contains Bootloader for DISCO_F769NI and MIMXRT1050_EVK platform
mbed_app.json             Build time configuration file

Prerequisites

To work with the pelion-border-router application, you need the following:

• Serial connection to your device with open terminal connection (baud rate 115200, 8N1). This is optional, but helps with debugging and confirming that the client connects to Device Management and the Wi-SUN interface is up.
• Arm Mbed CLI installed. See installation instructions.
  • Make sure that all the Python components are in par with the pip package requirements.txt list from Mbed OS.
• Pelion Device Management account.
• An API key (with Administrators group privilages) for your Device Management account. The API key is needed for auto-generating the developer certificate and for firmware update.

Memory Consumption

On border router the memory that is needed on board depends on network size. The RAM memory needed for a node on a network is about 650 bytes and needed KV store size is about 100 bytes for a node. KV store is needed to store Wi-SUN parameters during power cycle. Some Wi-SUN parameters need to be stored to KV store periodically, e.g. once in an hour. The size of periodically stored parameters is less than hundred bytes.

Configuring and compiling pelion-border-router application for DISCO_F769NI

1. Clone the repository if not done yet:

git clone https://github.com/PelionIoT/pelion-border-router.git

2. Go to pelion-border-router and deploy the dependencies:

cd pelion-border-router
mbed deploy

3. Configure Mbed CLI to use your Device Management account and board for DISCO_F769NI.

mbed target DISCO_F769NI
mbed toolchain GCC_ARM

4. Download a developer certificate from Device Management Portal.

5. Copy the mbed_cloud_dev_credentials.c file to the root folder of the example application.

6. Create update-related configuration and credentials using the manifest-tool python package:

   1. Upgrade to manifest-tool version 2.2.0 or higher:

      pip install --upgrade manifest-tool
      

   2. Initialize the developer environment:

      manifest-dev-tool init --access-key <Device Management access key>
      

      Note: When you create a firmware update image for a deployed device, you must use the same update-related configuration and credentials (update private key, public key certificate, update_default_resources.c and configuration files) you used in the original device firmware image. Therefore, you need to skip running this command as your environment should be already initialized.

7. Configure the application for your Wi-SUN network:

   • Use the Wi-SUN certificate definitions file configs/wisun_certificates.h, or generate your own Wi-SUN certificates (recommended) file to the same location.
   • Ensure the required Wi-SUN certificates (in file configs/wisun_certificates.h) are valid (WISUN_ROOT_CERTIFICATE, WISUN_SERVER_CERTIFICATE, WISUN_SERVER_KEY), and match the settings you are using with the border router. Invalid certificates or certificates that don't match prevent mesh network formation.
   • Use the configuration mesh-iface-start-control in JSON file to decide whether to start the mesh interface automatically or not.
     • Set the value of mesh-iface-start-control to "BLOCK" to prevent starting of mesh interface automatically. In this mode, various configurations of mesh interface can be configured from Pelion server before starting it. There is a timeout, after which the mesh interface will be started automatically. This timeout can be configured using mesh-iface-start-timeout parameter of the JSON file. Setting the value of mesh-iface-start-timeout to 0 will prevent the starting of mesh interface for infinite time.
     • Set the value of mesh-iface-start-control to "CONTINUE" to start the mesh interface automatically. In this mode, the mesh interface will be started right after registering to the Pelion. The parameter mesh-iface-start-timeout has no effect in this mode.

Tip: Use the same Mbed OS version in the border router and the application (Device Management Client).

Note: When you go to production, please do not use the example Wi-SUN certificate files provided as is due to security reasons.

8. Wi-SUN configuration: mbed_app.json file contains configuration for Pelion Border Router application. The Wi-SUN specific parameters are listed below.

   Field	Description
   wisun-network-name	Network name for Wi-SUN the network, MUST be same for all the devices in the network
   wisun-regulatory-domain	Defines regulatory domain, refer to ws_management_api for correct values for your region.
   wisun-operating-class	Defines operating class, limited by the regulatory domain
   wisun-operating-mode	Defines the operating mode, limited by the regulatory domain
   wisun-uc-channel-function	Unicast channel function
   wisun-bc-channel-function	Broadcast channel function
   wisun-uc-fixed-channel	Fixed channel for unicast
   wisun-bc-fixed-channel	Fixed channel for broadcast
   wisun-uc-dwell-interval	Unicast dwell interval. Range: 15-255 milliseconds
   wisun-bc-interval	Broadcast interval. Duration between broadcast dwell intervals. Range: 0-16777216 milliseconds
   wisun-bc-dwell-interval	Broadcast dwell interval. Range: 15-255 milliseconds
   certificate-header	Wi-SUN certificate header file
   root-certificate	Root certificate
   own-certificate	Own certificate
   own-certificate-key	Own certificate's key

Regulatory domain, operating class and operating mode are defined in the Wi-SUN PHY-specification.

9. Backhaul connectivity: The Pelion border router application should be connected to a backhaul network. This enables the border router to connect to the pelion server as well as the Wi-SUN mesh network to the internet or a private LAN. The application supports Ethernet backhaul connectivity:

10. Enable Dual-Bank mode on DISCO_F769NI:

    • Connect the device using STLink-Utility software
    • Go to Target->Option Bytes. Uncheck nDBANK option.
    • Apply and disconnect.

11. Compile the application for DISCO_F769NI:

mbed compile -m DISCO_F769NI -t GCC_ARM

Enabling external RADIUS server interface

You can enable external RADIUS server interface on the Pelion Border Router by setting RADIUS server IPv6 address and shared secret on Wi-SUN configuration: mbed_app.json

The external RADIUS server specific parameters are listed below.

| Field                               | Description                                                   |
|-------------------------------------|---------------------------------------------------------------|
| `radius-server-ipv6-address`        | RADIUS Server IPv6 address in string format (e.g. \"2001:1234::1\") |
| `radius-shared-secret`              | RADIUS shared secret; ASCII string or sequence of bytes |
| `radius-shared-secret-len`          | RADIUS shared secret length; If length is not defined, strlen() is used to determine RADIUS shared secret length |

Running the pelion border router application

1. Find the binary file pelion-border-router.bin in the BUILD folder.
2. Copy the binary to the USB mass storage root of the development board. It is automatically flashed to the target MCU. When the flashing is complete, the board restarts itself. Press the Reset button of the development board if it does not restart automatically.
3. The program begins execution.
4. Open the serial connection, for example PuTTY.
5. Obtain your device's Device ID either from device console logs or from Device Management Portal. When the client has successfully connected, the terminal shows:

   Client registered
   Endpoint Name: <Endpoint name>
   Device ID: <Device ID>
   

6. To verify the connection with Device Management Portal:
   • Log in to Device Management Portal.
   • Select Device directory from the menu on the left.
   • When your device is listed on the Devices page, it is connected and available. Your device is now connected and ready for the firmware update. For development devices, the Endpoint name and Device ID are identical.

Updating the Firmware

1. To update the firmware on your device:

   manifest-dev-tool update-v1 \
       --payload-path pelion-border-router_update.bin \
       --device-id <Device ID>
       --wait-for-completion
   

2. When the update starts, the client tracing log shows:

   Update progress = 0%
   

3. After this, the device reboots automatically and registers to Device Management.

Application resources

The list of supported resources and corresponding parameters are listed below.

Resource Path	Resources	Values
33455/0/13	Mesh Interface Control (Get & Put Allowed)	"CONTINUE" - Start Mesh Interface Automatically. "BLOCK" - Prevent Starting of Mesh Interface Automatically.
33455/0/14	Application State (Only Get Allowed)	"Waiting Permission" - Waiting Permission to Start the Mesh Interface. "Wi-SUN Booting" - The Mesh Interface has been Started. "Wi-SUN Active" - The Mesh Interface is Connected.

Program Flow

1. Initialize, connect and register to Pelion DM
2. Initialize and bring up Wi-SUN Interface

Serial connection settings

Serial connection settings are as follows:

• Baud-rate = 115200.
• Data bits = 8.
• Stop bits = 1.

If there is no input from the serial terminal, press the Reset button of the development board.

In the PuTTY main screen, save the session, and click Open. This opens a console window showing debug messages from the application. If the console screen is blank, you may need to press the Reset button of the board to see the debug information. The serial output from the pelion border router looks something like this in the console:

Mbed Bootloader
Update image is older
[DBG ] Active firmware up-to-date
booting...
[INFO][App ]: Pelion Border Router Application
[INFO][App ]: Fetching Backhaul Interface
[INFO][App ]: Fetching Mesh Interface
[INFO][App ]: Connect to Backhaul Interaface
[INFO][IPV6]: Start Bootstrap
[INFO][addr]: Tentative Address added to IF 1: fe80::280:e1ff:fe24:1c
[INFO][addr]: DAD passed on IF 1: fe80::280:e1ff:fe24:1c
[INFO][addr]: Tentative Address added to IF 1: 2001:14b8:1830:b000:280:e1ff:fe24:1c
[INFO][icmp]: Route: ::/0 Lifetime: 60 Pref: 0
[INFO][Ndns]: DNS Server: 2001:14b8:1830:8000::1 from: fe80::208:a2ff:fe0d:53 Lifetime: 60
[INFO][Ndns]: DNS Search List: 0b:6c:6f:63:61:6c:64:6f:6d:61:69:6e:00 Lifetime: 60
[INFO][icmp]: Route: ::/0 Lifetime: 60 Pref: 0
[INFO][Ndns]: DNS Server: 2001:14b8:1830:8000::1 from: fe80::208:a2ff:fe0d:53 Lifetime: 60
[INFO][Ndns]: DNS Search List: 0b:6c:6f:63:61:6c:64:6f:6d:61:69:6e:00 Lifetime: 60
[INFO][addr]: DAD passed on IF 1: 2001:14b8:1830:b000:280:e1ff:fe24:1c
[INFO][IPV6]: IPv6 bootstrap ready
[INFO][App ]: Backhaul Interface connected with IP 2001:14b8:1830:b000:280:e1ff:fe24:1c