Effect of mqtt qos1 duplicates

ChirpStack Network Server
1

Assuming everything in the system is set to use MQTT QOS1, what is the expected behavior of receiving duplicates (due to qos1)

For example:

  • Gateway-bridge sends an uplink packet from pkt_fwd, but network server receives duplicate mqtt message due to qos1
  • Network/app server “tx” publish sends a packet down to gateway, and gateway receives duplicate cmd/down mqtt message due to qos1
2

The network server will dedupe uplinks from the gateway bridge if they are received in a short enough time window. Dupes over a longer window will need to be handled by your application code.

I would not recommend using QoS1 between network/app servers and MQTT server.