Large device twins with Azure - Causes disconnect when response to get twin request exceeds ~2k.

RE: Large device twins with Azure - Causes disconnect when response to get twin request exceeds ~2k.

Øyvind — Mon, 28 Jun 2021 12:03:50 GMT

Hello,

I will provide an answer to this as Didrik is currently on vacation.

I've asked internally about this feature and it has not been implemented. Please contact you local RSM for more roadmap information.

Kind regards,
Øyvind

RE: Large device twins with Azure - Causes disconnect when response to get twin request exceeds ~2k.

JVantol — Tue, 15 Jun 2021 20:45:42 GMT

Didrik,

Did you ever find out anything more with this? It seems that Azure has a feature in preview which is part of RFC6066 that allows the TLS fragment size to be negotiated.

https://docs.microsoft.com/en-us/azure/iot-hub/iot-hub-tls-support#tls-maximum-fragment-length-negotiation-preview

https://datatracker.ietf.org/doc/html/rfc6066#section-4

Is this something we can make use of to mitigate this problem?

RE: Large device twins with Azure - Causes disconnect when response to get twin request exceeds ~2k.

Didrik Rokhaug — Thu, 25 Mar 2021 14:13:46 GMT

Hi,

[quote user=""]Increase the size of the TLS packet that the Nordic stack can handle.[/quote]

It is not possible to increase the segment size in the TLS stack in the modem.

However, it is possible to run the TLS stack on the application core, where you can set the TLS segment size however you want.

This will of course come at a RAM and flash cost on the application core. To see how it can be done, you can take a look at the Serial LTE Modem, where it can be enabled by a Kconfig option and an overlay configuration file.

When it comes to the two first ideas, I am not familiar enough with Azure to give an answer now. But, I have asked the developers of the azure_iot_hub library for their input, and will come back to you when I get an answer.

Best regards,

Didrik