nRFCloud CoAP Message Acknowledgement ??

[Avgerinos89]

Hello

I would like to ask how robust is a CoAP connection to nRFCloud using the nRF9160 device. In case of a network disconnection is it possible that we might have a message loss?
Does the nRFCloud library includes a message acknowledgement mechanism to ensure the robustness of the message transfer?

Thank you

[Achim Kraus]

Not sure, what exactly your case is.

I would assume, your device sends a CON request. If the request (device -> cloud) or ack/response (cloud -> device) gets lost, it's the device which needs to retransmit the request (see RFC 7252, 4. Message Transmission). With that it's the zephyr coap client of your device, which needs to retransmit the request. The cloud needs only to apply the mechanisms for "deduplication", if required.

There are also a "separate responses" (RFC 7252, 5.2.2 Separate), but I guess, you don't use it.

From my experience, losing the response on network disconnection is very rare. It's much more frequently the case, that the request isn't sent, because after wakeup the device detects, that the network is lost.