MQTT TLS connect blocking

RE: MQTT TLS connect blocking

Hakon — Fri, 23 Sep 2022 11:58:14 GMT

[quote user="Achevillard"]Do you know the minimum version of the nrf SDK needed to support UDP with MQTT ?[/quote]

It is not supported at all. MQTT is TCP based exclusively, so if you want to use UDP you should consider using CoAP instead.

RE: MQTT TLS connect blocking

Achevillard — Thu, 08 Sep 2022 15:56:27 GMT

Hi,

thank you for your answer. It really help our understanding of this behavior.

You said that we should use UDP if possible. Do you know the minimum version of the nrf SDK needed to support UDP with MQTT ? and for the modem firmware version ?

We are currently using version 1.9.1 and I would like to know if we need to upgrade.

Regards

Antoine

RE: MQTT TLS connect blocking

Hakon — Thu, 08 Sep 2022 12:37:38 GMT

Using TCP over NB-IoT is not recommended, you should rather use UDP if possible.

"There are three TLS connections in the log. 1st and 3rd TLS connection is successfully established. The 2nd TLS connection fails to timeout.

The same problem is visible in all three TLS connections. The NB-IoT connection is so slow that server starts to send TCP re-transmissions during the TLS handshake.

The Server Hello message contains TLS handshake protocol messages: Server Hello, Certificate, Server Key Exchange, Certificate Request, and Server Hello Done. It's length is 3583 bytes and it is split to six TCP segments. In all TCP connections the whole content of Server Hello is re-transmitted in TCP level. In the failing connection the TCP re-transmission is not completed in time and timeout ends the TLS handshake.

I am afraid that the only option here is to increase the TCP re-transmission interval in server side. Constant re-transmissions are lowering the throughput and preventing the TLS handshake to complete in time."

RE: MQTT TLS connect blocking

Hakon — Tue, 06 Sep 2022 14:07:57 GMT

Thanks

RE: MQTT TLS connect blocking

Achevillard — Thu, 25 Aug 2022 14:28:09 GMT

Hi

here are the trace of the modem. The bug appears 24' after the start

devzone.nordicsemi.com/.../trace_2D00_2022_2D00_08_2D00_25T13_2D00_34_2D00_33.144Z.bin

I hope that can help you fix this issue.

Regards

Antoine

RE: MQTT TLS connect blocking

Achevillard — Wed, 24 Aug 2022 07:39:48 GMT

Hi

I can activate UART1 as it is used as I2C for another function of my product.

Is there a way to change the uart by default of the modem trace and set it to uart0 (the one that I use to debug my application) ?

Regards,

Antoine

RE: MQTT TLS connect blocking

Achevillard — Mon, 22 Aug 2022 09:09:42 GMT

Hi

Sorry for the delay, the company was in vacation.

As I have a custom board, I haven't the modem trace activated.

I will activate and send you modem trace as soon as I can.

Regards,

Antoine

RE: MQTT TLS connect blocking

Hakon — Mon, 01 Aug 2022 10:43:56 GMT

Do you have a modem trace from this?

RE: MQTT TLS connect blocking

Achevillard — Tue, 26 Jul 2022 13:19:30 GMT

Hi,

I have the modem version 1.3.2. And I got the same bug as this ticket that I found searching for an explanation for this behavior on internet.

I didn't find in the changelog of mfw 1.3.x the correction of the bug.

Regards,

Antoine

RE: MQTT TLS connect blocking

Hakon — Tue, 26 Jul 2022 13:14:49 GMT

Hello,

[quote user=""]I have found in the devzone that is a known bug that should have been corrected in modem version 1.3.0.[/quote]

where did you get this from? The ticket you linked to has the bug occurring in mfw 1.3.0.