Semtech UDP packet-forwarder backend

The Semtech UDP packet-forwarder backend abstracts the UDP protocol.

It is compatible with:

  • v1 of the protocol
  • v2 of the protocol
  • Modified format used by the Kerlink iBTS containing the (encrypted) fine-timestamp


When the semtech_udp backend has been enabled, make sure your packet-forwarder global_conf.json or local_conf.json is configured correctly, under gateway_conf, the server_address, serv_port_up and serv_port_down must be configured so that data is forwarded to the LoRa Gateway Bridge instance.

"gateway_conf": {
	"gateway_ID": "AA555A0000000000",
	"server_address": "localhost",
	"serv_port_up": 1700,
	"serv_port_down": 1700,


The LoRa Gateway Bridge can be deployed either on the gateway (recommended) and “in the cloud”. In the latter case, multiple gateways can connect to the same LoRa Gateway Bridge instance.

When the LoRa Gateway Bridge is deployed on the gateway, you will benefit from the MQTT authentication / authorization layer and optional TLS.

Packet-forwarder re-configuration over MQTT

The Semtech UDP backend supports the re-configuration of the packet-forwarder over MQTT using the config Commands.

This works as follow:

  • The LoRa Gateway Bridge will periodically send stats Events containing the current configuration version.
  • LoRa Server processes these stats events and when a Gateway Profile is associated with the gateway, it will compare the configuration version.
  • In case the Gateway Profile version is newer, it will send a config command to the LoRa Gateway Bridge.
  • LoRa Gateway Bridge will then read the base_file, update it and writes it to the output_file.
  • It then restarts the packet-forwarder using the restart_command causing the packet-forwarder to reload its configuration.

For the above to work, you must configure the Mandaged packet-forwarder configuration section in the lora-gateway-bridge.toml.