The question, as mentioned in the title, is what causes the tx option field with the value 0x01 (disable ack) exactly. I assumed it disables the aps layer acknowledgement and the additional aps retries. But they occur in any way with aps acknowledgment disabled, too. The retry counter of the tx status frame counts still, sometimes till 60. I think this is a bit too much for the mac layer retries. Or there are also retries in nwk layer?
Regards Toby