RE: Question about IV index and sequence number SDK v4.1

huybk213 — Tue, 23 Jun 2020 00:36:02 GMT

Dear Mr Hung,

I understood your answer

If node 3 need to listen secure network beacon, how can i do this? It listen beacon by default or i need to trigger an event to put node 3 enter listen mode?

Thanks.

RE: Question about IV index and sequence number SDK v4.1

huybk213 — Mon, 22 Jun 2020 15:20:35 GMT

Thank you in advanced.

RE: Question about IV index and sequence number SDK v4.1

Hung Bui — Mon, 22 Jun 2020 12:19:58 GMT

Hi Huy,

If you have a look at the Bluetooth Mesh Spec v1.0.1 at section 3.8.4 you can find this:

If a node is absent from a mesh network for a period of time, it can scan for Secure Network beacons (see Section 3.10.1) or use the IV Index Recovery procedure (see Section 3.10.6), and therefore set the IV Index value autonomously.

Node 3 when it couldn't communicate with other node would need to listen to Secure Network beacons. After it receive a Secure Network Beacon it will follow the IV Index Recovery procedure to update the IV index hence join the network again.

This is already handled in net_beacon.c module. By default the Secure Network beacon is sent every 10 seconds. So on average Node 3 would need to listen around 5 seconds before it can catch the Secure Network beacon and start communicate again.