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wiki:wiki3:faq_multicast_3.x [2019/03/28 11:05] tda |
wiki:wiki3:faq_multicast_3.x [2019/06/21 15:44] (current) tda |
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- | ===== What is Unicast and Multicast ? ===== | + | ===== What are Unicast and Multicast? ===== |
Unicast messages are sent to a single end-device and multicast messages are sent to multiple end-devices. All devices of a multicast group must share the same multicast address and associated encryption keys. | Unicast messages are sent to a single end-device and multicast messages are sent to multiple end-devices. All devices of a multicast group must share the same multicast address and associated encryption keys. | ||
- | All end-devices must listen to the multicast channel in order to get multicast messages (end-devices must be C-class). The best use-cases for Multicast is Lighting domain and Firmware update. | + | All end-devices must listen to the multicast channel in order to receive multicast messages (end-devices must be C-class). The best use-cases for Multicast are Lighting domain and Firmware update. |
- | ===== How can I know that multicast messages are correctly received by my end-devices ? ===== | + | ===== How can I know that multicast messages are correctly received by my end-devices? ===== |
- | There is no ACK for Multicast messages. So we don't know if the multicast message has been received by all end-devices. | + | There is no ACK for Multicast messages. So from the WMC side, we cannot know if the multicast message has been received by all end-devices. |
- | ===== What is the mantadory information to create a Multicast group ? ===== | + | ===== What are the requirements to create a Multicast group? ===== |
- | The mandatory information is : \\ | + | The mandatory requirements are : \\ |
- | * a Cluster name | + | * a cluster name |
- | * a Multicast address: DevAddr, a 32 bit network address (must be unique and not belong to an existing end-device)\\ | + | * a multicast address: DevAddr, a 32 bit network address (must be unique and not belong to an existing end-device)\\ |
- | * the Application session key (AppSKey) and Network session key (NWkSKey) used for frames encryption, 32 digits hexadecimal string. | + | * the application session key (AppSKey) and network session key (NWkSKey) used for frames encryption, 32 digits hexadecimal string. |
- | * radio settings: a fixed frequency in MHz (float32)and a DataRate (a string formatted as "SFxxBWyyy" with xx from 7 to 12 and yyy = 125/250/500 for LoRa modulation or yyy=5000 for FSK modulation) | + | * radio settings: a fixed frequency in MHz (float32) and a DataRate (a string formatted as "SFxxBWyyy" with xx from 7 to 12 and yyy = 125/250/500 for LoRa modulation or yyy=5000 for FSK modulation) |
* a frame counter: FCntDown | * a frame counter: FCntDown | ||
* the LoRaWAN MAC version: for Europe 868 MHz, select 1.0.2 MAC version and Regional parameters B revision to be compatible with WMC 2.x | * the LoRaWAN MAC version: for Europe 868 MHz, select 1.0.2 MAC version and Regional parameters B revision to be compatible with WMC 2.x | ||
The multicast address and associated network session key and application session key must come from the application layer. \\ | The multicast address and associated network session key and application session key must come from the application layer. \\ | ||
- | Class-C Multicast downlinks SHALL NOT carry MAC commands. | + | Class-C multicast downlinks SHALL NOT carry MAC commands. |
- | ===== Can several Muticast groups have the same multicast adress ? ===== | + | ===== Can several Multicast groups have the same multicast adress? ===== |
Yes. The same multicast adrress can be used by several Multicast groups. | Yes. The same multicast adrress can be used by several Multicast groups. | ||
- | ===== Can a end-device belong to several Multicast groups ? ===== | + | ===== Can an end-device belong to several Multicast groups? ===== |
- | Yes. A end-device can belong to several multicast groups. | + | Yes. An end-device can belong to several Multicast groups. |
- | ===== Which gateways are chosen for a C-Multicast DataDown ? ===== | + | ===== Which gateways are chosen for a C-Multicast DataDown? ===== |
- | LNS selects gateways according to the dutycycle and the coverage of each gateway. | + | The LNS selects gateways according to the dutycycle and the coverage of each gateway. |
- | In all cases, a gateway cannot be selected if its duty cycle is over the maximum limit or if downlink is not allowed by its owner. | + | In any case, a gateway cannot be selected if its duty cycle is over the maximum limit or if downlink is not allowed by its owner. |
- | If a end-device has never transmitted data, it won't be taken into account for the choice of gateways used for multicast DataDown. | + | If an end-device has never transmitted data, it won't be considered when doing the selection of gateways used for Multicast DataDown. |
- | ===== Which gateways are choosen for a Unicast DataDown ? ===== | + | ===== Which gateways are choosen for a Unicast DataDown? ===== |
- | LNS selects gateways according to their SNR (Signal/Noise ratio). The gateway with the higher SNR (lowest noise) is choosen in priority. | + | The LNS selects gateways according to their SNR (Signal/Noise ratio). The gateway with the higher SNR (lowest noise) is choosen in priority. |
- | ===== Is it possible that a end-device receive a C-Multicast DataDown from 2 different gateways at the same time ? ===== | + | ===== Is it possible that a end-device receive a C-Multicast DataDown from multiple gateways at the same time? ===== |
- | For the moment, this case is not managed. | + | This case is not managed by the LNS yet. |