Multitech Gateway Bridge onboard - Downlink not sent

Gateways
1

Hi,

I am new to both LoRaWAN and chirpstack. I have configured a multitech conduit AEP by converting it to an mLinux version and installed the lora packet forwarder usb (1.4.1 r11) and gateway bridge 3.4.0_r1 (I tried 3.7.1_r1 with the same results) following the guide on chirpstack.io. I setup the network and application server on Azure again following the guide on chirpstack.io.

Messages sent from a lora device can be seen on the application server and the device successfully joins. On a SDR I can clearly see the uplink and the downlink messages. But when the next message is sent to the server, I expect a downlink to change the spreading factor on the device. When I do a tcpdump on the gateway (sudo tcpdump -AUq -i lo port 1700) I can see the uplink data as well as the expected downlink data, but the downlink is never sent. I can see this on a SDR. The periodic status message also shows that the downlink was sent. Here is an extract of the tcpdump with a rx packet that was successfully received as wel as a tx packet that is not sent out:

19:43:29.106349 IP localhost.49233 > localhost.1700: UDP, length 216
E...A.@.@............Q........[.........{"rxpk":[{"tmst":4057247420,"chan":6,"rfch":0,"freq":867.700000,"stat":1,"modu":"LORA","datr":"SF12BW125","codr":"4/5","lsnr":10.5,"rssi":-56,"size":29,"data":"QGBGBgCACwAChDHQ4sCACt/dPUczm+P10l0ynwY="}]}                                                                                                                                                                                                                                                                                                                                                                                                                                         
19:43:29.139901 IP localhost.1700 > localhost.49233: UDP, length 4
E.. B.@.@..............Q......[.
19:43:30.939511 IP localhost.1700 > localhost.35005: UDP, length 195
E...B.@.@.......................{"txpk":{"imme":false,"rfch":0,"powe":14,"ant":0,"brd":0,"tmst":4058247420,"freq":867.7,"modu":"LORA","datr":"SF12BW125","codr":"4/5","ipol":true,"size":17,"data":"YGBGBgCFCgADUv8AAb88VvY="}}                                                                                                                                                                                                                                                                                                                          
19:43:39.172012 IP localhost.35005 > localhost.1700: UDP, length 12
E..(C.@.@..................'..k.........
19:43:39.178644 IP localhost.1700 > localhost.35005: UDP, length 4
E.. C.@.@.....................k.
19:43:49.304192 IP localhost.35005 > localhost.1700: UDP, length 12
E..(DL@.@..v...............'.g..........
19:43:49.311821 IP localhost.1700 > localhost.35005: UDP, length 4
E.. DM@.@..}.................g..
19:43:56.354142 IP localhost.49233 > localhost.1700: UDP, length 158
E...G.@.@............Q..................{"stat":{"time":"2020-03-24 17:43:56 GMT","lati":-25.00000,"long":28.00000,"alti":1600,"rxnb":2,"rxok":2,"rxfw":2,"ackr":100.0,"dwnb":2,"txnb":2}}                                                                                                                                                                                                                                                                                                                          
19:43:56.377596 IP localhost.1700 > localhost.49233: UDP, length 4
E.. G.@.@..............Q........

I have no idea of where else to look and what to try. Any help will be appreciated.

2

Hi Nemesis,

can you please tell how this worked with you . I have multitech conduit I change it to mlinux version, I followed all the steps on chirpstack website, from chirpstack gateway bridge to chirpstack application server. on another side, I make the multitech installation where I now have chirpstack gateway bridge and lora packet forwarder installed on the gateway. while on another side, I have chirpstack gateway-bridge and chirpstack-network-server and chirpstack application server are installed not on the gateway, this is by following all the instruction of the chirpstack . Hence, I have all these installed and the gateway connected to the internet. Therefore, how I can connect all these together and start to see the data on chirpstack- application - server or even on the chirpstack- network-server.
on another side, previously when the multitech have the AEP firmware, it was very easy to set the gateway keys, but now how I can setup the gateway keys by the mlinux. I need instruction, a key instruction on configuration all these together.

please help me if you can. I highly appreciated

3

Hey,

I followed the Azure getting started guide: https://www.chirpstack.io/guides/microsoft-azure/. The configuration is also well documented on the chirpstack website: https://www.chirpstack.io/gateway-bridge/install/config/

Make sure you understand the architecture: https://www.chirpstack.io/overview/architecture/. It sounds like you installed the gateway bridge on both the gateway and your server. You only require it on either, preferably on the gateway.

My issue documented above was due to the round trip time from where I am (South Africa) to the azure servers (US) and back and the downlink message was received too late by the gateway to be able to send the message over LoRa. The issue was resolved by changing the rx1_delay to 2 seconds up from the default 1 second.

4

Thanks a lot Nemesis