port link-flap threshold

Function

The port link-flap threshold command sets the maximum number of link flapping events on an interface.

The undo port link-flap threshold command restores the default maximum number of link flapping events on an interface.

By default, the maximum number of link flapping events is 5.

Format

port link-flap threshold threshold-value

undo port link-flap threshold

Parameters

Parameter	Description	Value
threshold threshold-value	Specifies the maximum number of link flapping events on an interface.	The value is an integer that ranges from 5 to 10. The default value is 5.

Views

Ethernet interface view, GE interface view, XGE interface view, MultiGE interface view, 25GE interface view, 40GE interface view, 100GE interface view, port group view

Default Level

2: Configuration level

Usage Guidelines

Usage Scenario

Link flapping occurs when the physical status of an interface frequently alternates between Up and Down due to network flapping or network cable faults. Link flapping causes frequent network topology changes and affects user communication. For example, two links work in primary/backup mode. If the interface of the primary link experiences frequent Up/Down transitions, flows are switched between the primary and backup links. Frequent service switchovers increase load of the device and may result in service data loss.

Link flapping protection can solve the problem. You can configure this function to disable an interface that frequently alternates between Up and Down. When the interface is Down, the network topology will not change frequently. In the preceding example, you can configure link flapping protection on the interface of the primary link to prevent frequent topology changes. When the system detects frequent physical status changes on the interface of the primary link, the system directly disables the interface to trigger a primary/backup link switchover. The backup link then steadily transmits services. The link flapping protection function involves the following parameters:

Number of link flappings: One link flapping refers to one interface Up/Down transition.
Link flapping period: It is a period during which the system counts the number of link flappings.

If the number of link flappings on an interface reaches the threshold within a link flapping period, the system disables the interface and records its status as ERROR DOWN(link-flap), indicating that the interface is Down because of link flappings. By default, after link flapping protection is enabled, an interface goes Down if its status changes five times within 10 seconds.

Prerequisites

The port link-flap threshold command configuration takes effect only after link flapping protection is enabled using the port link-flap protection enable command on the interface.

Precautions

If you run the port link-flap threshold command multiple times in the same interface view, only the latest configuration takes effect.

Example

# Set the maximum number of link flapping events on GE0/0/1 to 10.

<HUAWEI> system-view
[HUAWEI] interface gigabitethernet 0/0/1
[HUAWEI-GigabitEthernet0/0/1] port link-flap threshold 10