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Configuration Guide - Interface Management

S1720, S2700, S5700, and S6720 V200R010C00

This document describes the principles and configurations of interfaces and provides configuration examples.

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Huawei uses machine translation combined with human proofreading to translate this document to different languages in order to help you better understand the content of this document. Note: Even the most advanced machine translation cannot match the quality of professional translators. Huawei shall not bear any responsibility for translation accuracy and it is recommended that you refer to the English document (a link for which has been provided).
Configuring Virtual Cable Test

Configuring Virtual Cable Test


Virtual cable test (VCT) technology uses time domain reflectometry (TDR) to detect the cable status. When pulse signals are transmitted in a cable, some energy of the signals is reflected at the end or a failure point on the cable. This phenomenon is called TDR. The VCT algorithm measures the time spent on transmitting pulse signals over a cable, reaching the failure point, and returning the pulse signals. The measured time is converted into the distance.

As shown in Figure 3-10, GE0/0/1 of SwitchA is connected to GE0/0/2 of SwitchB using a network cable. A failure point exists on the network cable. After VCT is configured on GE0/0/1, the system generates pulse signals. When the pulse signals reach the failure point, some energy is reflected to the GE0/0/1. In this example, the distance between SwitchA and the failure point is L, the period from sending pulse signals to receiving reflected pulse signals is T, and the transmission rate of pulse signals in the cable is V. The following formula is used to calculate the distance between the failure point and GE0/0/1:

L = (V x T)/2

Figure 3-10  VCT

VCT detects the network cable fault type and identifies the failure point, facilitating fault location on network cables.


  1. Run:


    The system view is displayed.

  2. Run:

    interface interface-type interface-number

    The interface view is displayed.

  3. Run:


    VCT is configured.

    • The test result is for reference only and may be inaccurate for network cables from some vendors.
    • 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 VCT. However, you are not advised to configure VCT on a combo electrical interface because services will be interrupted.
    • VCT can be configured on an XGE optical interface that has a GE copper module installed.
    • VCT can be configured on a GE optical interface that has a GE copper module installed.

Checking the Configuration

Run the display virtual-cable-test interface-type interface-number command in any view to check the latest VCT result on an Ethernet interface.

Updated: 2019-12-28

Document ID: EDOC1000141936

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