mesh updates under Zephyr

RE: mesh updates under Zephyr

Hung Bui — Tue, 20 Sep 2022 09:06:19 GMT

Hi Andy,

It's actually possible to trigger IV index update by using cmd_iv_update_test() , CONFIG_BT_MESH_IV_UPDATE_TEST need to set to y.

RE: mesh updates under Zephyr

AndyM — Mon, 19 Sep 2022 14:35:02 GMT

I provisioned 4 devices on Friday.

Everything works as expected

So far the index has 't changed.

This morning I send the mesh iv-update command and got

mesh iv-update
Transitioned to IV Update Normal state
IV Index is 0x00000000
I'll let you now in a couple days when the index changes

Thank you

RE: mesh updates under Zephyr

Hung Bui — Mon, 19 Sep 2022 11:24:16 GMT

Hi Andy,

Yes as far as I know it's the feature that supported by the mesh stack by default.
Could you try to test if the IV index only moved to 1 or 2 and then you provision a new node with IV index 0 . Would it manage to join the network after provisioning and wait for 10 minutes ?

RE: mesh updates under Zephyr

AndyM — Sat, 17 Sep 2022 14:11:24 GMT

[quote userid="2121" url="~/f/nordic-q-a/92016/mesh-updates-under-zephyr/386639"]Basically the node need to listen for Secure Network beacon to update the IV index. I'm not so sure why in your case the node couldn't update that. [/quote]

This sounds like something that should be handled by the mesh stack. Perhaps there is a config setting that needs to be enabled?

RE: mesh updates under Zephyr

Hung Bui — Fri, 16 Sep 2022 12:14:52 GMT

Hi Andy,

[quote user=""] Is there a public API to get the current IV index from a provisioned device?[/quote]

As far as I know there isn't one but you can get the IV index from a node that has CONFIG_BT_MESH_IV_UPDATE_TEST=y using the following command: https://github.com/zephyrproject-rtos/zephyr/blob/9926b90bf6c3642cc37e3b91bf859f75b25a3169/subsys/bluetooth/mesh/shell/shell.c#L559-L572

2. I don't think it's a good idea. You will break the Bluetooth Mesh spec and will run out of sequence number after some time.

3. Please have a look at section 3.10.6 IV Index Recovery procedure in the Bluetooth mesh profile specification v1.0.1. Basically the node need to listen for Secure Network beacon to update the IV index. I'm not so sure why in your case the node couldn't update that.

There is a caveat if the current IV Index is greater than your current IV Index +42 it will not be possible to recover. Please have a look at page 130: