# Loop detection

### 1. Summary

This page is for configuring the settings for loop detection.

This function monitors whether a loop is occurring bysending its loop detection frame from the port and whether the framereturns to itself or not.

### 2. Top page

This is the top page for the loop detection.

#### 2.1. System settings

- Displays the system settings of loop detection.

- The table items are explained below.

  - Displays the loop detection settings for the entire system.

  - Displays the setting for whether to disable Port Blocking immediately or periodically after the loop is resolved.

  - Displays the setting for automatic recovery from Shutdown (errdisable state).

  - Press the "Setting" button to display the page for configuring the loop detection settings for the entire system.

- Resetting the loop detection status

  - You can immediately resolve the loop detection states (e.g., Shutdown) by reset feature.

#### 2.2. Interface settings

- Displays the settings and operating status of loop detection for each interface.

- The table items are explained below.

  - Check box
    Select the check box for bulk settings or to initialize the settings.

  - Port
    Displays the interface name.

  - Loop detection
    Displays the settings of loop detection for the interface.

  - Port Blocking
    Displays the settings of Port Blocking function.
    If it is enabled, the function blocks frames when a loop is detected.

  - Status
    Displays the operating status of loop detection.

    - Operating
      The loop detection function is operating.

    - Detected
      Loop has been detected. Communication is continued.

    - Blocking
      Blocking the frames. (Restart the communication in 5 seconds after the loop has been resolved)

    - Shutdown
      Shutting down the port. (Restart the communication in 5 minutes after shutting down the port)

    - Stopped
      The loop detection function is stopped.
      Normally, the state becomes "Stopped" when the loop detection setting is disabled.
      If it is stopped by other factors, the following factors are indicated in parentheses.

      - Mirror port
        If it is a port with mirroring settings (mirror port)

      - STP
        You can use theloop detection function with spanning tree. However, the function worksonly when the spanning tree status of the corresponding port is"Forwarding".

- Press the "Setting" button to display the page for configuring the selected interface settings.

- Press the "Specify all" button to configure the settings for all interfaces with the check box selected.

- Press the "Return to defaults" button to initialize the settings for all interfaces with the check box selected.

  - Each of the default settings are shown below.

    - Loop detection: Enabled

    - Port Blocking: Enabled (Block frames when a loop is detected)

- Press the "Update" button to update the table of interface settings.

### 3. System settings page

This page is for configuring the interface settings for loop detection.
Enter the settings, and then press the "Confirm" button.
If there are no mistakes in the input content of the confirmation screen, press the "OK" button.

#### 3.1. System settings

- Specify whether to enable or disable the loop detection function for the entire system.
  Even if set to enable, the loop detection function for an individual port does not work if the port’s setting is disabled.

- If this function is used with a spanning tree, the spanning tree takes precedence.

### 4. Interface settings page

This page is for configuring the interface settings for loop detection.
Enter the settings, and then press the "Confirm" button.
If there are no mistakes in the input content of the confirmation screen, press the "OK" button.

#### 4.1. Interface settings

- Loop detection
  Specify whether to enable or disable the loop detection function for the target interface.
  However, even if set to enable, the loop detection function does not work in the following cases.
  (1) The loop detection function for the entire system is disabled.
  (2) The target interface is a port with mirroring settings. (mirror port)
  (3) Used with spanning tree, and spanning tree status of the target interface is not "Forwarding".

- Port Blocking
  Specify whether to enable or disable the Port Blocking function for the target interface.
  If set to enable, the function blocks frames when a loop is detected.

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