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CX11x, CX31x, CX710 (Earlier Than V6.03), and CX91x Series Switch Modules V100R001C10 Configuration Guide 12

The documents describe the configuration of various services supported by the CX11x&CX31x&CX91x series switch modules The description covers configuration examples and function configurations.
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Maintenance

Maintenance

You can detect the cable status, perform loopback tests on an Ethernet interface to check whether the interface forwarding is normal, and clear traffic statistics on the Ethernet interface.

Configuring VCT

Context

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

As shown in Figure 4-8, GE1/17/1 on SwitchA connects to GE1/17/2 on SwitchB with a network cable. There is a failure point in the network cable. After VCT is configured on GE1/17/1, the system generates pulse signals. After the pulse signals reach the failure point, some energies are reflected to the transmit end. In this example, the distance between SwitchA and the failure point is L, and the period from sending pulse signals to receiving reflected pulse signals is T, the transmission rate of pulse signals in the cable is V. The formula used to calculate the distance between the failure point and GE1/17/1 is as follows:

L = (V × T )/2

Figure 4-8 VCT

VCT can detect the fault type of a network cable and identify failure points to help locate network cable faults.

Procedure

  1. Run:

    system-view

    The system view is displayed.

  2. Run:

    interface interface-type interface-number

    The interface view is displayed.

  3. Run:

    virtual-cable-test

    The VCT function is configured.

    NOTE:
    • Electrical interfaces and 10GE optical interfaces connected to an SFP-GE electrical interface module support the setting.
    • When 10GE optical interfaces use SFP-GE copper modules and the interfaces on the two ends of the link are both Up, the test result may be not accurate and is only for reference.
    • The test result is only for reference and may be inaccurate for cables from some vendors.
    • Running the virtual-cable-test command may affect services on the interface in a short period of time.
    • Before configuring VCT, shut down the remote interface or remove the network cable between the local and remote interfaces. Otherwise, signals from the remote interface may make the test result inaccurate.

Checking the Configuration

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

Configuring Internal Loopback Detection

Context

When testing some special functions such as locating an Ethernet fault, you must enable loopback detection on the Ethernet interface to check whether the interface is working properly. When no fault occurs on the Ethernet interface, the physical interface status is always Up after loopback detection is enabled. If a fault occurs on the Ethernet interface, the interface status is Down.

  • The loopback detection function (configured using the loopback command) affects other functions; therefore, the interface or link cannot work properly. When the test is complete, you must run the undo loopback command in real time to disable loopback. The original configuration is restored after loopback detection is disabled.

Procedure

  1. Run:

    system-view

    The system view is displayed.

  2. Run:

    interface interface-type interface-number

    The interface view is displayed.

  3. Run:

    loopback internal

    Internal loopback detection is configured on the Ethernet interface.

    By default, loopback detection is disabled on an Ethernet interface.

  4. Run:

    commit

    The configuration is committed.

Checking the Configuration

Run the display interface [ interface-type [ interface-number ] ] command in any view or the display this interface command in the interface view to check the current interface status. For details, check the Loopback field in the command output.

Clearing Interface Statistics

Context

To monitor the status of an interface or locate faults on the interface, you can collect traffic statistics about the interface. Before collecting traffic statistics on an Ethernet interface within a period, delete the existing traffic statistics on this interface.

The traffic statistics on an Ethernet interface cannot be restored after they are cleared. Exercise caution before clearing the statistics.

Procedure

  • Run the reset interface counters [ interface-type [ interface-number ] ] command to clear the statistics on the specified interface.
  • Run the reset interface [ interface-type interface-number ] virtual-cable-test command to clear the cable test results of the interface.
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Updated: 2019-08-09

Document ID: EDOC1000041694

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