mesh sequence number reaches FFFFFF

[William.wei]

hi Support team,

Customer tested mesh SDK4.2, and now had one question:

their product is end node, and once button pressed, MCU is waked up and  send the message to server.which looks like ----reset and button press.

after a long time, find out the sequence number reaches 0xFFFFFF, and net_state_seqnum_alloc api will return NRF_ERROR_FORBIDDEN as below.

Even after reset, it still fails, how to solve this problem.

Regards,

William.

[Mttrinh]

Hi,

In the issue above they are seeing a sequence number exhaustion.

You can try one or more of the following:

Decrease NETWORK_SEQNUM_FLASH_BLOCK_SIZE (this will increase the use of flash, but low or no effect if it is frequent resets. This shouldn't be much bigger than a value that you expect to be used up as one approaches the next reset)

Decrease IV_UPDATE_TIMEOUT_PERIODIC_SAVE_MINUTES(This will increase the use of flash.It should be lower than expected uptime between resets).

Decrease NETWORK_MIN_IV_RECOVERY_INTERVAL_MINUTES (You won't be able to qualify as this will break the specification).

Turn on test mode so you can do IV Update whenever (You won't be able to qualify as this will break the specification).

Also, take a look at this thread for more info.

[Mttrinh]

William.wei said:

or i should change NETWORK_SEQNUM_FLASH_BLOCK_SIZE  to 3, since the message will be sent by three times as default, anyway, product goes to system off mode, and will reset next time.

NETWORK_SEQNUM_FLASH_BLOCK_SIZE defines the number of sequence numbers between every write to flash. In case of power failure, the device will resume transmissions with the first sequence number in the next block. A larger block size means that the device can do fewer resets between every IV Update, while a smaller will result in a reduced lifetime for the flash hardware. This depends on how often your device resets. They could for example try to decrease this value to 512.

The test mode is defined in the specification only for the purpose of executing the qualification tests, it is not defined meant to be used for usual use cases.