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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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Configuring Loopback Detection

Configuring Loopback Detection

Loopback detection can detect loops on the network connected to the device.

Enabling Loopback Detection

Context

An interface sends loopback detection packets to detect loopbacks only after loopback detection is enabled on the interface.

  • If an interface has been added to VLANs in untagged mode, the interface sends one copy of untagged detection packet regardless of how many VLANs the interface has been added to. untagged loopback detection packets are discarded and loops cannot be detected. Therefore, configure the device to detect loops in a specified VLAN.

  • If an interface has been added to VLANs in tagged mode, loopback detection must be enabled in specified VLANs, and the interface sends the loopback detection packets of the VLAN that contains the interface and has loopback detection enabled.

After VLAN IDs are specified, the interface sends one copy of untagged loopback detection packets and multiple copies of tagged loopback detection packets with the specified VLAN tags.

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-detect enable(interface view)

    Loopback detection is enabled on the interface.

    By default, loopback detection is disabled on an interface.

  4. (Optional) Run:

    loopback-detect vlan { vlan-id1 [ to vlan-id2 ] } &<1-10>

    A VLAN ID is specified for loopback detection packets.

    By default, no VLAN ID is specified for loopback detection packets.

    NOTE:

    The interface sends loopback detection packets with specified VLAN tags only when the following conditions are met.

    • A VLAN has been created.
    • The interface has been added to the specified VLAN in tagged mode.
    • A VLAN ID has been specified for loopback detection packets using the loopback-detect vlan { vlan-id1 [ to vlan-id2 ] } &<1-10> command.

  5. Run:

    commit

    The configuration is committed.

(Optional) Configuring an Action to Perform After a Loopback Is Detected

Context

After loopback detection is enabled on an interface, the interface periodically sends detection packets and checks whether loopback packets are received. When a loopback is detected on an interface, the system sets the interface status to loopback, minimizing impact on the system and the entire network.

Procedure

  • Configuring an action to perform after a loopback is detected in the system view
    1. Run:

      system-view

      The system view is displayed.

    2. Run:

      loopback-detect action error-down

      The action to perform on the interface is set to error-down when a loopback is detected on the interface.

      The default action is alarm.

      When the system detects a loopback on an interface, it sets the interface to error-down state and sends an alarm.

      NOTE:
      • You can run the error-down auto-recovery cause loopback-detect interval interval-value command to sets the time after which the interface in error-down state automatically recovers.

      • If the action to perform on the interface is alarm, inter-device loopback may suppress loopback detection on other interfaces on the local device. In this situation, set the action to error-down or use STP to prevent loopback.

    3. Run:

      commit

      The configuration is committed.

  • Configuring an action to perform after a loopback is detected in the interface view
    1. Run:

      system-view

      The system view is displayed.

    2. Run:

      interface interface-type interface-number

      The interface view is displayed.

    3. Run:

      loopback-detect action { error-down | alarm }

      The action to perform on the interface is set when a loopback is detected on the interface.

      By default, when a loopback is detected on an interface, the action is as follows:
      • If the loopback-detect action error-down command is not used in the system view, an alarm is generated.
      • If the loopback-detect action error-down command is used in the system view, the interface is shut down.
      NOTE:

      If the loopback-detect action (interface view) and loopback-detect action error-down commands are executed in the interface view and system view respectively, the configuration in the interface view takes effect.

    4. Run:

      commit

      The configuration is committed.

(Optional) Setting the Interval Between Sending Loopback Detection Packets on an Interface

Context

An interface sends loopback detection packets at intervals.

Procedure

  1. Run:

    system-view

    The system view is displayed.

  2. Run:

    loopback-detect transmit interval packet-interval-time

    The interval between sending loopback detection packets is set.

    By default, the interval between sending loopback detection packets is 5 seconds.

  3. Run:

    commit

    The configuration is committed.

Checking the Configuration

Procedure

  • Run the display loopback-detect command to check the loopback detection configuration and status of loopback detection enabled interfaces.
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Updated: 2019-08-09

Document ID: EDOC1000041694

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