Technical Tip: Power Fault: Error Type 17 (Port is yet undefined)

Description

This article describes how to troubleshoot the error Power Fault: Error Type 17 (Port is yet undefined) observed on FortiSwitch PoE.

Scope

FortiSwitch devices providing PoE.

Solution

Most Likely Cause:

The PSE (Power Sourcing Equipment) controller chip on the FortiSwitch is physically damaged/burnt. Error Type 17 means the PSE controller cannot detect or communicate with the PSE chip — the chip is either destroyed or its firmware is corrupted beyond recovery.

Common triggers for the damage:

• Power surges/fluctuations from the AC mains (no UPS or inadequate power conditioning).

• Lightning/transient voltage spikes on RJ45 PoE ports exceeding the 1KV surge specification (no Ethernet surge protectors installed).

• Connecting two PSE ports together (e.g., cascading two PoE switches via RJ45 copper ports instead of SFP) — this can short/burn the PSE chip on one or both switches.

• High ambient temperature (can cause temporary Error Type 17, but usually becomes permanent damage).

Immediate Checks:

Run these commands to confirm the diagnosis:

1. Check PoE status on all ports
   
   

get switch poe inline

Look for: Fault:4 state and Error Type 17 (port is yet undefined) on all/most ports

2. Check PoE firmware version (identifies PSE chip type):
   
   

get hardware status

3. Check system status and BIOS version:
   
   

get system status

Troubleshooting Steps:

Step 1: Attempt Power Cycle Recovery (rare but worth trying):

This is the only potential software-level fix. In most cases it will NOT work, but a small number of units have recovered:

1. Disconnect ALL devices/cables from all switch ports (especially PoE ports).

2. Execute:
   
   

execute shutdown

3. Unplug the power cable from the switch.

4. Wait at least 5–10 minutes (let the device fully cool down and discharge).

5. Reconnect power only (no Ethernet cables).

6. Check:
   
   

get switch poe inline

• If ports return to Searching or Delivering Power state, the issue was temporary (likely temperature or transient voltage).

• If ports still show Error Type 17, the PSE chip is permanently damaged; proceed to RMA.

Step 2: Attempt BIOS + PoE Firmware Upgrade (if power cycle partially helped):

If the switch is functional (non-PoE ports work, management accessible), try upgrading:

Upgrade BIOS to latest version for the required model:

execute bios-update <image-file>

Upgrade PoE firmware:

Download the appropriate PoE firmware image from Fortinet Support. Open a new ticket to TAC to evaluate the upgrade of PoE firmware or proceed with RMA directly.

Use the image matching the switch model and FortiSwitchOS version.


Step 3: Verify Environmental Factors:

Check the installation environment to prevent recurrence on replacement units:

• Is the switch connected to a UPS or power conditioner?

• Are Ethernet surge protectors installed on RJ45 PoE ports?

• Are any two PoE switches cascaded via copper RJ45 ports? (This is a known cause — use SFP ports for switch-to-switch uplinks).

• Is ambient temperature within operating specs (0–40°C)?

• Is the AC power supply voltage stable and within range?

Step 4: Initiate RMA:

If Error Type 17 persists after a power cycle (with no devices connected), RMA is the only resolution. The PSE chip is physically damaged and cannot be repaired via software.

Collect debug report for RMA/FA:

diagnose debug report

This generates a diagnostic file to attach to the RMA. Proceed to record a video showing the serial number of the device as well as the reported behavior.

Key Configuration to Verify:

Verify PoE configuration (before RMA, to rule out config issues):

show switch poe

Check if any ports have PoE explicitly disabled:

config switch physical-port
    edit port1
        set poe-status enable
    next
end

Verify PoE budget and mode:

get switch poe inline

Check: Unit power budget, Unit Guard Band, Unit Power Mode:

Preventive Measures:

1. Install a UPS or power regulator on the AC supply side to prevent power fluctuations/surges.

2. Install Ethernet surge protectors on all RJ45 PoE ports (lightning surge must be < 1KV per PSE chip spec).

3. Never connect two PSE/PoE ports together: always use SFP ports for switch-to-switch uplinks.
   
   

Summary:

Power Fault: Error Type 17 (Port is yet undefined) = the PSE controller cannot detect the PSE chip.
In the vast majority of cases, this means the PSE chip is physically burnt/damaged due to power surges, lightning, or improper cascading of PoE switches. RMA is the resolution. No software fix, firmware upgrade, or configuration change can repair a burnt PSE chip.