Communication between gateway bridge and packet-forwarder

ChirpStack Application Server
1

Hello,

We’re trying to make our own LoRa infrastructure with LoRa Server.
We have a Debian server which has LoRa Gateway Bridge - LoRa Server - LoRa App Server.
The “gateway” is a Raspberry Pi with a Dragino HAT and the Dual Channel Packet Forwarder from Dragino too.
Our nodes are ASCOEL CM868LR and CM868LRTH.
LoRa App Server : version 3.0.0
LoRa Server : version 3.0.1
Mosquitto : 3.1.1
LoRa Gateway Bridge : 3.0.1

We’re stuck on tthe Join/Accept loop.

LoRa_jrja
LoRa_jrja683×519 31.5 KB

The way Node → App Server seems to work. But there’s something wrong with the Gateway Bridge → Gateway/Node.
All seems fine until the Gateway bridge → Dragino/Pi communication.

LoRa_pkts
LoRa_pkts944×759 61.5 KB

As you can see, there’s no frames transmitted.

Here’s a snippet from the mosquitto log

gateway/b827ebffffb96de6/event/up {"phyPayload":"AKqqqgAAAQAAspowM2Q0fg7Dx1yp/7k=","txInfo":{"frequency":868100000,"modulation":"LORA","loRaModulationInfo":{"bandwidth":125,"spreadingFactor":7,"codeRate":"4/5","polarizationInversion":false}},"rxInfo":{"gatewayID":"uCfr//+5beY=","time":null,"timeSinceGPSEpoch":null,"rssi":-44,"loRaSNR":9,"channel":0,"rfChain":0,"board":0,"antenna":0,"location":null,"fineTimestampType":"NONE","context":"0aqPnA=="}}

This one is the UPLINLK JoinRequest, followed immediately by the DOWNLINK JoinAccept

gateway/b827ebffffb96de6/command/down {"phyPayload":"IGHjXaDmfO3vReny/rTtoG2RvoPA52x+Y94EGoBdcLQV","txInfo":{"gatewayID":"uCfr//+5beY=","frequency":868100000,"power":14,"modulation":"LORA","loRaModulationInfo":{"bandwidth":125,"spreadingFactor":7,"codeRate":"4/5","polarizationInversion":true},"board":0,"antenna":0,"timing":"DELAY","delayTimingInfo":{"delay":"5s"},"context":"0aqPnA=="},"token":11015}

And a STATS request, immediately after.

gateway/b827ebffffb96de6/event/stats {"gatewayID":"uCfr//+5beY=","ip":"172.30.3.49","time":"2019-09-02T14:31:05Z","location":{"latitude":0,"longitude":0,"altitude":0,"source":"GPS","accuracy":0},"configVersion":"","rxPacketsReceived":1,"rxPacketsReceivedOK":1,"txPacketsReceived":0,"txPacketsEmitted":0,"metaData":{}}

At the same time, on the Gateway Bridge :

Sep 02 16:30:51 srv-lorawan lora-gateway-bridge[50799]: time="2019-09-02T16:30:51+02:00" level=debug msg="backend/semtechudp: received udp packet from gateway" addr="172.30.3.49:42759" protocol_version=1 type=PushData

Sep 02 16:30:51 srv-lorawan lora-gateway-bridge[50799]: time="2019-09-02T16:30:51+02:00" level=info msg="integration/mqtt: publishing event" event=up qos=0 topic=gateway/b827ebffffb96de6/event/up

Sep 02 16:30:51 srv-lorawan lora-gateway-bridge[50799]: time="2019-09-02T16:30:51+02:00" level=debug msg="backend/semtechudp: sending udp packet to gateway" addr="172.30.3.49:42759" protocol_version=1 type=PushACK

Sep 02 16:31:04 srv-lorawan lora-gateway-bridge[50799]: time="2019-09-02T16:31:04+02:00" level=debug msg="backend/semtechudp: received udp packet from gateway" addr="172.30.3.49:42759" protocol_version=1 type=PushData

Sep 02 16:31:04 srv-lorawan lora-gateway-bridge[50799]: time="2019-09-02T16:31:04+02:00" level=info msg="integration/mqtt: publishing event" event=stats qos=0 topic=gateway/b827ebffffb96de6/event/stats

Sep 02 16:31:04 srv-lorawan lora-gateway-bridge[50799]: time="2019-09-02T16:31:04+02:00" level=debug msg="backend/semtechudp: sending udp packet to gateway" addr="172.30.3.49:42759" protocol_version=1 type=PushACK

There’s an UP event, but no DOWN… It’s the STATS after.
Where should we look for finding what happens to the DOWN instruction ?

2

Hi !
We worked on this and found something quite “strange” to us.
It looks like MQTT doesn’t have the join notification

Sep 04 14:02:10 srv-lorawan lora-app-server[801]: time="2019-09-04T14:02:10+02:00" level=info msg="backend/joinserver: request received" message_type=JoinReq receiver_id=DEVICE_APPEUI sender_id=000000 transaction_id=4000169142
Sep 04 14:02:10 srv-lorawan lora-app-server[801]: time="2019-09-04T14:02:10+02:00" level=info msg="device-keys updated" dev_eui=0e7e346433309ab2
Sep 04 14:02:10 srv-lorawan lora-app-server[801]: time="2019-09-04T14:02:10+02:00" level=info msg="backend/joinserver: sending response" message_type=JoinAns receiver_id=000000 result_code=Success sender_id=DEVICE_APPEUI transaction_id=4000169142

When it works fine, it seems that there is a line like this, but we don’t have it.

level=info msg="handler/mqtt: publishing join notification" topic="application/3/node/xxxxxxx/join"

So it seems that MQTT isn’t aware of the success.

mosquitto_sub -v -t "application/#"

returns nothing, like a wildcard on all the topics.

3

Ok, we got it working.
Our packet forwarder didn’t support downlink. We found one with this functinnality and it all act better.

4

Hi Bruce,

Can you provide more details on your solution ?

5

I used Bokse001’s packet forwarder with uplink and downlink : https://github.com/bokse001/dual_chan_pkt_fwd/tree/dual_chan_pkt_fwd_up_down
I also updated the whole loraserver package (server + bridge + app).
But we can’t go further.
Our nodes received the JoinAccept packet and begun to act like if they were properly registered.
Shortly after the Tx packet was sent by our gateway, the sensor started to blink. After that, as they’re door sensors, the embedded LED started to blink each time the magnet was moved nearer or farther to it, a comportment which wasn’t saw until this. And the endless “JoinRequest / JoinAccept” loop was broken !
But… as we said in French “there is always a but”.
Loraserver don’t see them as “activated devices”.

I’ve been in touch with Dragino’s support and they told me that this HAT don’t work well with OTAA devices and that we should move on a solution with a SX1301 chip. We’ll do that. :slight_smile: