Cable Test

The Port Cable Test feature enables you to determine the cable connection status on a selected port. You can also obtain an estimate of the length of the cable connected to the port, if the PHY (Physical Interface Transceiver) on the ports supports this functionality.



The cable test feature is supported only for copper cable. It is not supported for optical fiber cable.

To access this page, click System > Port > Cable Test.

The page displays with additional fields when you click Test Cable. The fields that display depend on the cable test results.

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Cable Test Fields

Field Description
Interface If the test has not been performed, this is the only field that displays. Select the interface to test.

After the test has been performed, this field shows the interface that was tested.

Cable Status This displays the cable status as Normal, Open, or Short.
  • Normal: The cable is working correctly.
  • Open: The cable is disconnected or there is a faulty connector.
  • Open and Short: There is an electrical short in the cable.
  • Cable Status Test Failed: The cable status could not be determined. The cable may in fact be working. This field is displayed after you click Test Cable and results are available.
Cable Length The estimated length of the cable. If the cable length cannot be determined, Unknown is displayed. This field shows the range between the shortest estimated length and the longest estimated length.
Note: This field displays a value only when the Cable Status is Normal; otherwise, this field is blank.
Failure Location The estimated distance from the end of the cable to the failure location.
Note: This field displays a value only when the Cable Status is Open or Short; otherwise, this field is blank.

Select a port and click Test Cable to display its status.

If the port has an active link while the cable test is run, the link can go down for the duration of the test. The test may take several seconds to run.

The command returns a cable length estimate if this feature is supported by the PHY for the current link speed. Note that if the link is down and a cable is attached to a 10/100 Ethernet adapter, then the cable status may display as Open or Short because some Ethernet adapters leave unused wire pairs unterminated or grounded.