Hello! I’m new to LoRa world and trying to get my head around the technology, building blocks and all of the terminology.
To start off I would appreciate some clarification in regards to TTN and a private LoRa server solution. As far as I understand you can’t point a lora node to a specific gateway. The node will connect to whatever will “see” in that moment. So, in general situation there could be more than 1 joinable gateway in the air. What happens if my node connects to TTN, whereas all my infrastructure is behind by ChirpStack solution? Is there a standard that forwards packets from TTN to my private server stack? How does it know about my infrastructure?
I guess I’m missing a key point, but I’m unable to find a clear explanation of the data flow in the case there a re multiple gateways/networks available.
Kindly asking you for some explanation or to point me to the right direction.
Thanks, Marko
Every gateway can potentially “hear” your message, but not every network can decode it.
If your “node” is using OTAA, it first sends a JOIN (DEV_EUI) message, every network might try to look if the “know” the device by “asking” the corresponding APP+JOIN-Server. If successful several keys are exchanged between node,network-server, app-server and join-server; the communication is then fully encrypted and can only be decrypted by the “network” having the “keys”. Everyone else will just see a DevAddr as the Identifier and some other connection related properties, the payload itself is still encrypted. The node does not really connect to any gateway, it exchanges keys and configuration for a network. The gateway “just” relays packets from/to the node to a network.
ABP is “all-keys” were already exchanged and configured in the corresponding network. (I’m leaving a lot of details out)
tl;dr: Everyone gets your messages, but only the network with the proper key can read the content and/or send you a message which can be read by the node.
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Now is crystal clear. That’s the missing puzzle. The GW is just a sort of transparent radio<–>LoraWAN protocol translator.
Thanks for your reply. Very concise and clear!