"strange" bad MIC packet

[astella]

To the kind attention of Nordic support team,

using Nordic ble sniffer, I can see these notifications, and there is sometime this bad MIC packet.

Our connection is not using any encryption (apparently). So, what could be the message? An error we are doing in user ble files, or could be related to something else?

Any suggestion from your side?

Thank you so much for your help, best regards

[Hung Bui]

Hi Stella, 

Could you please check if the CRC value of the packet is matched, not an incorrect CRC ? 
If possible please upload the sniffer trace file here. 

I suspect that it's simply a corrupted packet received by the sniffer trace. In that case we will have CRC mismatch. 

[astella]

Hi Hung, thank you. Here the sniffing trace

prova_ol.pcapng

[Hung Bui]

Hi Stella, 

From what I I can see the CRC was correct. So it might be not the packet corruption issue.

However, it's most likely not the issue with the data packet. And more likely the glitch with the sniffer itself. 
Normally if a packet has a wrong MIC, the peer device should terminate immediately. 

You can see that the Bluetooth core spec v5.2 Vol 1 Part F section 2.58: 

In your case it seems the connection continued normally. 

I would suggest to use another sniffer as reference to sniff in parallel to cross check, preferably a professional BLE sniffer for example Ellisys or Frontline. 

[astella]

Thank you