virtual-cable-test

Function

The virtual-cable-test command tests the cable connected to an Ethernet electrical interface and displays the test result.

The following switch models and interfaces do not support this command:

Multi-GE interfaces on the S5720-28X-PWH-LI-AC, S5732-H24UM2CC, S5732-H48UM2CC, S6720-32C-SI-AC, S6720-32C-SI-DC, S6720-32C-PWH-SI-AC, S6720-32C-PWH-SI, S6720-52X-PWH-SI, S6720-56C-PWH-SI-AC, and S6720-56C-PWH-SI
XGE electrical interfaces on the ES5D21X08T00 card

Format

virtual-cable-test

Parameters

None

Views

Ethernet interface view, GE interface view, XGE interface view, 25GE interface view

Default Level

3: Management level

Usage Guidelines

Usage Scenario

If the cable is faulty, the interface is in Down state or the interface rate is abnormal even if it is in Up state. You can run the virtual-cable-test command to check whether the cable works properly. According to the command output, you can locate and rectify cable faults.

If the cable works properly, the total length of the cable is displayed.
If the cable cannot work properly, the distance between the interface and the fault point is displayed.

Precautions

The test result is only for reference and may be inaccurate for cables of some vendors.
If the detection result is Unknown, you are advised to use the cable analyzer to perform the test.
The test result is related to the cable signal attenuation. When the cable length is shorter than 3 m, the cable signal attenuation mostly results from the connector, not the cable. The test result is therefore invalid.
Running the virtual-cable-test command may affect services on the interface in a short period of time, and the interface in Up state may alternate between Up and Down.
Combo electrical interfaces support cable tests, but cable tests are not recommended on combo electrical interfaces because services will be interrupted.
This command can be used on an XGE optical interface or GE optical interface when the interface has a GE copper module installed.
After a 25GE optical interface is configured to work at the rate of 1 Gbit/s using the port mode ge command and has a GE copper module installed, the virtual-cable-test command can be configured on the interface.
On the S2720-EI, S5720-LI, S5735-L, S5735S-L, S5735S-L-M, S5720S-LI, S5730-SI, S5730S-EI, S6720-LI, S6720-SI, S6720S-SI, S6720S-LI, S5720-SI, S5735-S, S5735S-S, S5735-S-I, S5720I-SI, and S5720S-SI, when a GE electrical interface works at a rate of 1000 Mbit/s or 100 Mbit/s, the test result is only for reference and may be inaccurate if the interface is in Up state.
On the S5720-EI, S5720-HI, S5730-HI, S6720-HI, S6720S-EI, S5732-H, S6730-H, S6730S-H, S6730-S, S6730S-S, and S6720-EI, when a GE electrical interfaceworks at a rate of 100 Mbit/s, the test result is only for reference and may be inaccurate.
On the S5731-H, S5731S-H, S5731-S, and S5731S-S, when a GE electrical interface works at a rate of 10 Mbit/s, 100 Mbit/s, or 1000 Mbit/s, the test result is only for reference and may be inaccurate.
The test result is only for reference and may be inaccurate when the interface is in the Up state or the remote interface is shut down.
The FE electrical port uses only two pairs of wire pairs. The two pairs of wire sequences used for VCT detection are unavailable.
When the GE electrical port works at the rate of 10 Mbit/s or 100 Mbit/s, only two pairs of cables are used to detect the VCT status. The other two pairs of cables do not detect and return the default result.
The virtual cable test (VCT) cannot be performed on multiple interfaces of the device at the same time.

Example

# Test the cable connected to GE0/0/1.

<HUAWEI> system-view
[HUAWEI] interface gigabitethernet 0/0/1
[HUAWEI-GigabitEthernet0/0/1] virtual-cable-test
Warning: The command will stop service for a while. Continue? [Y/N]y
Info: This operation may take a few seconds. Please wait for a moment..........done.
Pair A length: 189meter(s)
Pair B length: 189meter(s)
Pair C length: 189meter(s)
Pair D length: 189meter(s)
Pair A state: Ok
Pair B state: Ok
Pair C state: Ok
Pair D state: Ok

**Table 1** Description of the virtual-cable-test command output
Item	Description
Pair A/B/C/D	Four pairs of circuits in a network cable.
Pair A length	Length of a network cable: The length is the distance between the interface and the faulty point if a fault occurs. The length is the actual length of the cable when the cable works properly. The default length is 0 m if the interface is not connected to any network cable. NOTE: If the cable length is displayed as Unknown, the cable status is OK, but the cable length test result cannot be used. If the cable status is Open (indicating open circuit), the cable length in the VCT result can be used. If the remote interface is shut down, the cable length in the VCT result can be used for combo electrical interfaces on the following switches: S2720-EI S5720-SI, S5720I-SI, S5720S-SI S5720-12TP-LI-AC, S5720-12TP-PWR-LI-AC, S5720-28TP-PWR-LI-AC, S5720S-28TP-PWR-LI-AC, S5720-28TP-PWR-LI-AC, S5720-28TP-LI-AC, and S5720-52X-LI-48S-AC If the remote interface is shut down, the cable length in the VCT result can be used for electrical interfaces on the following switches: S2720-EI S5720-EI S5720-HI S5730-HI S5731-H S6720-HI S6730-H S6730S-H S5720-16X-PWH-LI-AC S5720-28X-PWH-LI-AC, S5720-28X-PWH-LI-ACF, and S5720-52X-LI-48S-AC S5730-SI S5730S-EI S6720-SI
Pair A state	Network cable status: Ok: indicates that the circuit pair is terminated normally. Open: indicates that the circuit pair is not terminated. Short: indicates that the circuit pair is short-circuited. Crosstalk: indicates that the circuit pairs interfere with each other. Unknown: indicates that the circuit pair has an unknown fault or the detection result is inaccurate.