Configuring Self-Loop Detection on the GE Interface

After the self-loop detection function is enabled, the self-loop on an interface can be detected and then the interface is blocked.


A router enabled with the loopback detect function periodically sends specially constructed loopback detect packets. If a self-loop exists on an interface, the loopback detect packets will be looped back to the router, and the router can then determine that a self-loop has occurred. A malicious attacker can trick a loopback-detect-enabled router into believing that a self-loop has occurred, by sending loopback detect packets obtained using Sniffer back to the router.

The GE interface self-loop detection function is used only for link self-loop tests in the service deployment phase. To prevent security risks, disable this function after services are running properly.

Do as follows on the routers:


  1. Run system-view

    The system view is displayed.

  2. Run interface gigabitethernet interface-number

    The GE interface view is displayed.

  3. Run loopback-detect enable

    The self-loop detection function is enabled.

  4. Run loopback-detect block block-time

    Set the delay time of the interface recovery after the self-loop on the interface is eliminated.

Copyright © Huawei Technologies Co., Ltd.
Copyright © Huawei Technologies Co., Ltd.
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