Issue link: https://read.uberflip.com/i/1428356
LoRaWAN Fragmented Data Block Transport v1.0.0 Specification ©2018 LoRa Alliance™ Page 8 of 30 The authors reserve the right to change specifications without notice. 3.1 PackageVersionReq & Ans 171 172 The PackageVersionReq command has no payload. 173 The end-device answers with a PackageVersionAns command with the following payload. 174 175 Field PackageIdentifier PackageVersion Size (bytes) 1 1 Table 2: PackageVersionAns 176 PackageIdentifier uniquely identifies the package. For the "fragmentation transport package" 177 this identifier is 3. 178 PackageVersion corresponds to the version of the package specification implemented by the 179 end-device. 180 3.2 FragSessionSetupReq & Ans 181 This message is used to setup a DL fragmentation transport session. 182 183 Table 3: FragSessionSetupReq 184 185 FragSession identifies the fragmentation session and contains the following fields 186 187 FragSession Fields RFU FragIndex McGroupBitMask Size (bits) 2bits 2bits 4bits Table 4: FragSessionSetupReq FragSession field 188 FragIndex [0 to 3] identifies one of the 4 simultaneously possible fragmentation sessions. 189 190 McGroupBitMask specifies which multicast group addresses are allowed as input to this 191 defragmentation session. Bit number X indicates if multicast group with McGroupID=X is 192 allowed to feed fragments to the defragmentation session. Unicast can always be used as a 193 source for the defragmentation session and cannot be disabled. For example, 4'b0000 194 means that only Unicast can be used with this fragmentation session. 4'b0001 means the 195 defragmentation layer MAY receive packets from the multicast group with McGroupID=0 and 196 the unicast address. 4'b1111 means that any of the 4 multicast groups or unicast may be 197 used. If the end-device does not support multicast, this field SHALL be ignored. 198 Note: the McGroupBitMask is a mechanism allowing tying a 199 defragmentation session to one or several specific multicast group 200 addresses in a given end-device. For example, a street lighting 201 controller end-device is part of 2 multicast groups, one used to control 202 the lamps and one for firmware updates. Only data fragments coming 203 from the second group shall be taken into account by the fragmented 204 transport layer. The first group shall only transport ON/OFF lamp 205 control packet and should not be allowed to transport firmware update 206 data. 207 208 NbFrag (Number of Fragments) specifies the total number of fragments of the data block to 209 be transported during the coming multicast fragmentation session. (example: 100 means 210 that the data block that is going to be multicasted will be divided in 100 fragments) 211 Field FragSession NbFrag FragSize Control Padding Descriptor Size (bytes) 1 2 1 1 1 4