RAK3172 duplicated uplink / same frame counter

Hi @beegee ,

Module: RAK3172
RUI3 V4.1.1
AT commands on UART2
Unconfirmed uplinks

The application on host controller is sending an uplink on every 10 minutes. Sporadically there is an extra uplink between the regular 10 minutes.
I found out the extra uplink is not comming from my application (there is no AT command on serial line), but possibly generated by RAK3172.

It is a copy of last uplink, with the same frame counter, thus generation a warning in the network server (Everynet).
After this extra uplink the next 10min payload is sent correctly, frame counter incremented.

Please, what is the reason for this unforeseen uplink and same frame counter?
Any suggestion on how to solve it?

Are you using confirmed packet mode? In that case, it can be the packet didn’t went through.

Beside of the same frame counter, what is the fPort used for this uplink? If it is fPort 0, it could be a status message requested by the LNS, e.g. in Chirpstack:

Hi @beegee ,

My uplinks are not confirmed.

First message is the valid one (1) and second (2) is the one generated by the system. Message (3) is valid again, frame counter incremented.

Follow the content of both messages with the same frame counter. Left side is valid message (1), right side is the unexpected message (2).

Part1

Part2

Looks like the packets are coming from two different gateways:
The first one has ID 647fda01c09 a 0000
The second one has ID 647fda01c09 0 0000

So the node is sending one packet, it is received by two gateways and forwarded by both to the LoRaWAN server.

The problem seems to be that your LNS doesn’t detect the duplicate packet from the second gateway and does not discard it.

No mistake of the RAK3172, it is sending the packet only once. You have to check in your LNS why it doesn’t detect the duplicate packet.

Hi @beegee ,

I talked to the LNS company, follow their evaluation:
The LNS is configured to discard repeated messages.
The messages have different “packet_id”, that means they are different messages.
According to them the “packet_id” is generated by the device.

Their suspect is the LoRaWAN stack, in the device, is somehow duplicating the message and sending it some short time later…

What do you think?

This is happening a few times everyday…

Enable debug output on the RAK3172 with AT+DEBUG=1
If the RAK3172 is sending the packet twice, you will see it in the UART log output.

I am using RAK3172’s in multiple devices around my house and I do not see the device sending messages on it’s own. I am convinced what you see are the same packet coming from two gateways.

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