04-Network Connectivity Command Reference

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05-Loop detection commands
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05-Loop detection commands 66.27 KB

Loop detection commands

display loopback-detection

Use display loopback-detection to display the loop detection configuration and status.

Syntax

display loopback-detection

Views

Any view

Predefined user roles

network-admin

network-operator

Example

# Display the loop detection configuration and status.

<Sysname> display loopback-detection

Loopback detection is enabled.

Loopback detection interval is 30 second(s).

Loopback is detected on following interfaces:

 Interface                Action mode

 GigabitEthernet1/0/1     None

Table 1 Command output

Field

Description

Action mode

Loop protection action:

·     Block—When a loop is detected on a port, the device performs the following operations:

¡     Logs the event.

¡     Disables the port from learning MAC addresses.

¡     Blocks the port.

·     None—When a loop is detected on a port, the device logs the event without taking any action on the port.

·     No-learning—When a loop is detected on a port, the device logs the event and disables the port from learning MAC addresses.

·     Shutdown—When a loop is detected on a port, the device performs the following operations:

¡     Logs the event.

¡     Shuts down the port to disable it from receiving or sending frames. The device automatically sets the port to the forwarding state after a time interval. Set the time interval by using the shutdown-interval command (see System Management Command Reference).

loopback-detection action

Use loopback-detection action to set the loop protection action on a per-port basis.

Use undo loopback-detection action to restore the default.

Syntax

In Layer 2 Ethernet interface view:

loopback-detection action { block | no-learning | shutdown }

undo loopback-detection action

In Layer 2 aggregate interface view:

loopback-detection action shutdown

undo loopback-detection action

Default

When the device detects a loop on a port, it logs the event without taking any action on the port.

Views

Layer 2 Ethernet interface view

Layer 2 aggregate interface view

Predefined user roles

network-admin

Parameters

block: Enables the block mode. If a loop is detected, the device performs the following operations:

·     Logs the event.

·     Disables MAC address learning.

·     Blocks the port.

Layer 2 aggregate interfaces do not support this keyword.

no-learning: Enables the no-learning mode. If a loop is detected, the device logs the event and disables MAC address learning on the port. Layer 2 aggregate interfaces do not support this keyword.

shutdown: Enables the shutdown mode. If a loop is detected, the device logs the event and shuts down the port. The device automatically sets the port to the forwarding state after the time interval set by using the shutdown-interval command (see System Management Command Reference).

Usage guidelines

To set the loop protection action globally, use the loopback-detection global action command.

The global action applies to all ports. The per-port action applies to the individual ports. The per-port action takes precedence over the global action.

Example

# Set the loop protection action to shutdown on GigabitEthernet 1/0/1.

<Sysname> system-view

[Sysname] interface gigabitethernet 1/0/1

[System-GigabitEthernet1/0/1] loopback-detection action shutdown

Related commands

display loopback-detection

loopback-detection global action

loopback-detection enable

Use loopback-detection enable to enable loop detection on a per-port basis.

Use undo loopback-detection enable to disable loop detection on a port.

Syntax

loopback-detection enable vlan { vlan-id-list | all }

undo loopback-detection enable vlan { vlan-id-list | all }

Default

Loop detection is disabled on ports.

Views

Layer 2 Ethernet interface view

Layer 2 aggregate interface view

Predefined user roles

network-admin

Parameters

vlan-id-list: Specifies a space-separated list of up to 10 VLAN items. Each item specifies a VLAN ID or a range of VLAN IDs in the form of vlan-id1 to vlan-id2. The value range for VLAN IDs is 1 to 4094. The ID for vlan-id2 must be equal to or greater than the ID for vlan-id1.

all: Specifies all existing VLANs.

Usage guidelines

You can enable loop detection globally or on a per-port basis. When a port receives a detection frame in any VLAN, the loop protection action is triggered on that port, regardless of whether loop detection is enabled on it.

Example

# Enable loop detection on GigabitEthernet 1/0/1 for VLAN 10 through VLAN 20.

<Sysname> system-view

[Sysname] interface gigabitethernet 1/0/1

[System-GigabitEthernet1/0/1] loopback-detection enable vlan 10 to 20

Related commands

display loopback-detection

loopback-detection global enable

loopback-detection global action

Use loopback-detection global action to set the global loop protection action.

Use undo loopback-detection global action to restore the default.

Syntax

loopback-detection global action shutdown

undo loopback-detection global action

Default

When the device detects a loop on a port, it logs the event without taking any action on the port.

Views

System view

Predefined user roles

network-admin

Parameters

shutdown: Enables the shutdown mode. If a loop is detected, the device logs the event and shuts down the port. The device automatically sets the port to the forwarding state after you set the time interval by using the shutdown-interval command (see System Management Command Reference).

Usage guidelines

To set the loop protection action on a per-port basis, use the loopback-detection action command in interface view.

The global action applies to all ports. The per-port action applies to the individual ports. The per-port action takes precedence over the global action.

Example

# Set the global loop protection action to shutdown.

<Sysname> system-view

[System] loopback-detection global action shutdown

Related commands

display loopback-detection

loopback-detection action

loopback-detection global enable

Use loopback-detection global enable to enable loop detection globally.

Use undo loopback-detection global enable to disable loop detection globally.

Syntax

loopback-detection global enable vlan { vlan-id-list | all }

undo loopback-detection global enable vlan { vlan-id-list | all }

Default

Loop detection is globally disabled.

Views

System view

Predefined user roles

network-admin

Parameters

vlan-id-list: Specifies a space-separated list of up to 10 VLAN items. Each item specifies a VLAN ID or a range of VLAN IDs in the form of vlan-id1 to vlan-id2. The value range for VLAN IDs is 1 to 4094. The ID for vlan-id2 must be equal to or greater than the ID for vlan-id1.

all: Specifies all existing VLANs.

Usage guidelines

You can enable loop detection globally or on a per-port basis. When a port receives a detection frame in any VLAN, the loop protection action is triggered on that port, regardless of whether loop detection is enabled on it.

Example

# Globally enable loop detection for VLAN 10 through VLAN 20.

<Sysname> system-view

[System] loopback-detection global enable vlan 10 to 20

Related commands

display loopback-detection

loopback-detection enable

loopback-detection interval-time

Use loopback-detection interval-time to set the loop detection interval.

Use undo loopback-detection interval-time to restore the default.

Syntax

loopback-detection interval-time interval

undo loopback-detection interval-time

Default

The loop detection interval is 30 seconds.

Views

System view

Predefined user roles

network-admin

Parameters

interval: Sets the loop detection interval in the range of 1 to 300 seconds.

Usage guidelines

With loop detection enabled, the device sends loop detection frames at the specified interval. A shorter interval offers more sensitive detection but consumes more resources. Consider the system performance and loop detection speed when you set the loop detection interval.

Example

# Set the loop detection interval to 10 seconds.

<Sysname> system-view

[Sysname] loopback-detection interval-time 10

Related commands

display loopback-detection

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