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Device managementPrinciples

Sequence number: general knowledge


One of the security features implemented by Sigfox is the sequence number. This article describes how this works and how to troubleshoot potential issues related to it.

General concept

The sequence number is part of the Sigfox protocol overhead and it is incremented with every message transmission. If the gap between a sequence number of a message and the following turns out to be significant, then it might be due to:

  • the device passed through a non-covered area
  • the device maker re-flashed a device firmware and this restarted the sequence number
  • someone tried to usurp the device identity

 

Depending on the severity of the sequence number gap, Sigfox will:

  • Show a "Warning" in the "events" tab on the "DEVICE" part of the Backend. 
  • Show an "Error" in the "events" tab on the "DEVICE" part of the Backend and interrupt the device message delivery.


Sequence gap warning and error triggers

Whether the sequence gap triggers a warning or an error depends on the number of messages sent by day and the magnitude of the gap. 
You can check in the table below what size of a gap triggers a warning or an error for each subscription type. 

 Messages per dayWarning trigger (gap magnitude)Error trigger (gap magnitude)
One2120
Silver501150
Gold1001300
Platinum1401420

 Note on platinum contract that the first day, this limit is caped at 300 messages

For security reasons, Sigfox is not providing more details on this topic.

 

 

Sequence number cycle

After a full cycle (4096 messages), the sequence number is reset.

 

Troubleshooting

If the messages transmitted by one of your devices are not delivered anymore due to the ERROR explained above, you can disengage its sequence number as follows:

  1. Log into the Backend and go to the "Device" tab
  2. Search the device
  3. Click on the "disengage sequence number" button in the "information" tab

Security warning

The sequence number is a security feature. Please only use this button if the cause of the sequence number gap is known.

 

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