Issue link: https://read.uberflip.com/i/1428395
LoRaWAN ® L2 1.0.4 Specification © 2020 LoRa Alliance ® Page 23 of 90 The authors reserve the right to change specifications without notice. Note: This means that an end-device will only acknowledge receipt of a 711 downlink confirmed frame NbTrans times. Similarly, an end-device will 712 only generate NbTrans uplinks following receipt of a frame with the 713 FPending bit set before incrementing its FCntUp. 714 715 Note: As the FCnt field carries only the least-significant 16 bits of the 716 32-bit frame counter, the server must infer the 16 most-significant bits of 717 the frame counter by observing the traffic. 718 4.3.1.6 Frame options (FOptsLen in FCtrl, FOpts) 719 The frame-options length field (FOptsLen) in FCtrl denotes the actual length of the frame 720 options field (FOpts) included in the frame. 721 FOpts transports MAC commands of a maximum length of 15 octets that are piggybacked 722 onto data frames; see Section 5 for a list of valid MAC commands. 723 If FOptsLen=0, the FOpts field SHALL be absent. If FOptsLen≠0, i.e. if MAC commands 724 are present in the FOpts field, the FPort value 0 SHALL NOT be used (FPort SHALL 725 either not be present or not equal to 0). 726 MAC commands SHALL NOT be present in the payload field and the frame options field 727 simultaneously. Should this occur, the end-device SHALL silently discard the frame. 728 729 4.3.1.7 Class B enabled bit (ClassB in FCtrl, uplink only) 730 731 The ClassB bit set to 1, in an uplink, signals to the Network Server that the end-device has 732 enabled class B and is now ready to receive scheduled downlink pings. Please refer to the 733 Class B section of the document for the Class B specification. 734 735 4.3.2 Port field (FPort) 736 If the frame payload field is not empty, the port field SHALL be present. If present, an FPort 737 value of 0 indicates that the FRMPayload contains only MAC commands; see Section 5 for 738 a list of valid MAC commands. FPort values 1..223 (0x01..0xDF) are application-specific. 739 FPort value 224 is dedicated to the LoRaWAN MAC layer test protocol. FPort values 740 224..255 (0xE0..0xFF) are reserved for use and allocation by the LoRa Alliance [TS008]. 741 The purpose of the FPort value 224 is to provide a dedicated FPort to run MAC 742 compliance test scenarios over-the-air on final versions of end-devices, without having to rely 743 on specific test versions of end-devices for practical aspects. The test is not supposed to be 744 simultaneous with live operations, but the MAC layer implementation of an end-device SHALL 745 be exactly the one used for the normal application. The test protocol is encrypted using the 746 AppSKey. This ensures that the Network cannot enable the end-device's test mode without 747 involving the end-device's owner. 748 749