Second JOIN when device is already connected

Hi @carlrowan

Please, what happens if the end device (RAK3172) is already connected to the network, successful JOIN, and I do a second JOIN?
I am trying to make sure the device is still connected and implemented a JOIN on every 24 hours. Is it a good strategy or should I use the LINKCHECK command before a JOIN?
Maybe 24h is too frequent…

Note: I understand sending only a JOIN command saves downlink in comparison to a LINKCHECK + JOIN.

Hi @IGtti ,

Rejoining creates new sessions keys and device address to your LoRaWAN device. It also resets frame counters. However, this might not be relevant to your application level.

Ideally, your end-device should only join once in its lifetime. Regardless if it goes out of range from a gateway, it should still be able to send packets again once it goes back to area/location with coverage.

If you perform rejoin, linkcheck or linkcheck+rejoin every hour, it might not be good long term once your application goes on scale. LoRaWAN Gateways right now are primarily halfduplex so when it send downlink, it will not be able to capture packets on that freq/DR setting.

Ok, clear. Thank s for the clarification.
I will keep the JOIN command only in case of a device reset.

It looks risk to not have any confirmation about the connection status. Even in a lower frequency do you recommend to implement any command (other than JOIN) to refresh this status?

Hi @IGtti

It depends on you application but maybe implementing linkcheck or confirmed uplink once in a while to check network connectivity wont hurt. However, this is already on detection of disconnect. Best if you can avoid disconnection by ensure uptime of LNS and gateway. Also ensure that the device is located in a location where there is still enough RF margin. Redundancy wont hurt as well.

Btw, if you no remote monitoring of the gateway status yet, that might be more critical than on the device side.

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