SFP receive power low warning set

This article explains why the event message  SFP receive power low warning set might appear in the syslog.

When a low power condition is detected on an SFP, a message similar to the following appears in the syslog:

The bus that the router uses to monitor the SFP and update diagnostic data is called “i2c” or IIC, for inter-integrated circuit. Conditions sometimes arise that cause the i2c to miss updates. As a result, you might see warnings and alarms regarding low power that subsequently clear. These should not affect traffic in any way.

This issue is seen more often when non-Juniper SFPs are used, because different SFP makers handle SFP monitoring in different ways. As long as you are not seeing a traffic impact along with the power warning, the message is safe to ignore.

If you are seeing a traffic impact, then the message could indicate a hardware problem with the SFP, the PIC into which it is installed, the FPC, or the fiber that is plugged into the SFP.

Perform these steps to determine the cause and resolve the problem (if any). Continue through each step until the problem is resolved.

1. Collect show command output.

Capture the output to a file (in case you have to open a technical support case). To do this, configure each SSH client/terminal emulator to log your session.

2. Analyze the show command output.

  • Determine if you are losing any traffic due to the message. Use the show interfaces extensive command to show traffic statistics, including dropped packets. If you use this command over time, you can see if the drops are incrementing.
  • If you are losing traffic, re-insert or swap out the SFP. See the instructions for DPC on MX960, which is similar to all other platforms for manipulating a SFP. If this fails to resolve the issue, try cleaning the fiber (electronically), or test the fiber on another link to verify that there is not a faulty fiber.
  • If the SFP and cable are confirmed to be fine, you can try swapping the PIC. See the instructions for a PIC on T4000 or similar documentation for your platform. If this does not resolve the issue, then the FPC that is reporting these messages should be replaced. If there is any doubt, examine the logs in Step 1 for further investigation.
  • Look for messages that occur at or immediately before the
    message. If no traffic loss is occurring with the message, no action is necessary, and the message can be ignored. If there is traffic loss, clean the fiber and perform the hardware swaps indicated in the above section.

3. If these efforts do not resolve the problem, contact your technical support representative to investigate the issue further.

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