Create multicast groups to send a downlink payload to multiple devices - Amazon IoT Core
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Create multicast groups to send a downlink payload to multiple devices

To send a downlink payload to multiple devices, create a multicast group. Using multicast, a source can send data to a single multicast address, which is then distributed to an entire group of recipient devices.

Devices in a multicast group share the same multicast address, session keys, and frame counter. By using the same session keys, devices in a multicast group can decrypt the message when a downlink transmission is initiated. A multicast group only supports downlink. It doesn't confirm whether the downlink payload has been received by the devices.

With Amazon IoT Core for LoRaWAN's multicast groups, you can:

  • Filter your list of devices by using the device profile, RFRegion, or device class, and then add these devices to a multicast group.

  • Schedule and send one or more downlink payload messages to devices in a multicast group, within a 48-hour distribution window.

  • Have devices temporarily switch to Class B or class C mode at the start of your multicast session for receiving the downlink message.

  • Monitor your multicast group setup and the state of its devices, and also troubleshoot any issues.

  • Use Firmware Updates-Over-The-Air (FUOTA) to securely deploy firmware updates to devices in a multicast group.

Amazon IoT Core for LoRaWAN's support for FUOTA and multicast groups is based on the LoRa Alliance's following specifications:

  • LoRaWAN Remote Multicast Setup Specification, TS005-1.0.0

  • LoRaWAN Fragmented Data Block Transportation Specification, TS004-1.0.0

  • LoRaWAN Application Layer Clock Synchronization Specification, TS003-1.0.0


Amazon IoT Core for LoRaWAN automatically performs the clock synchronization for the device according to the LoRa Alliance specification. Using function AppTimeReq, it replies the server-side time to the devices that request it using ClockSync signaling.

The following shows how to create your multicast group and schedule a downlink message.