No channel found for frequency

Question

I have a ChirpStack server in the EU and one in the US. They are configured the same.

There are 3 regions enabled: eu868, us915_1, us915_7

There are two message brokers, one in the US and one in the EU. Gateways in the EU connect to the EU broker, and gateways in the US connect to the US broker.

The eu868 ChirpStack region config connects to the EU broker, and the us915 configs connect to the US broker. I realize the ChirpStack servers will receive messages from both brokers, and messages from both regions will be handled by both servers.

I am seeing two common error message in the logs, but they are different for the two different servers. The number at the beginning is a count of messages in the last 20000 log lines (with log level 'trace' enabled, so a LOT of log data).

US Server:

      1  chirpstack::uplink: Deduplication error error=No channel found for frequency: 867300000, dr: 0
      2  chirpstack::uplink: Deduplication error error=No channel found for frequency: 867500000, dr: 0
      2  chirpstack::uplink: Deduplication error error=No channel found for frequency: 867700000, dr: 0
      1  chirpstack::uplink: Deduplication error error=No channel found for frequency: 867900000, dr: 0

EU server:

    367  chirpstack::uplink: Deduplication error error=Zero items in collect set

I am parcularly concerned about the "No channel found..." message exhibted only in the US server for EU based gateway messages (verified EU based gateway messages due to gateway ID not shown). The region_eu868.toml is identical on both servers, the channel definitions have not been modified, and the config contains the frequencies mentioned in the log. Example:

    [[regions.gateway.channels]]
      frequency=867300000
      bandwidth=125000
      modulation="LORA"
      spreading_factors=[7, 8, 9, 10, 11, 12]

    [[regions.gateway.channels]]
      frequency=867500000
      bandwidth=125000
      modulation="LORA"
      spreading_factors=[7, 8, 9, 10, 11, 12]

I do miss messages from EU devices, and I am assuming it is related to this error. How do I interpret and remedy both of these errors?

Orne Brocaar · Answer

Deduplication error error=No channel found for frequency: 867300000, dr: 0

This means that after resolving the region configuration for the uplink (based on region_XXXXX.toml MQTT configuration: MQTT broker and / or MQTT topic prefix), the uplink frequency can not be resolved into a channel number. In other words, the uplink frequency is unknown for the region configuration.

The [[regions.gateway.channels]] sets the gateway configuration (in case you are using the Concentratord, this will automatically configure your gateway). In the above case, you are interested in the [[regions.network.extra_channels]] as this is used to map frequencies to channel numbers. See also: https://github.com/chirpstack/chirpstack/blob/master/chirpstack/configuration/region_eu868.toml#L276.

No channel found for frequency

1 Answers