port link-flap interval

Function

The port link-flap interval command sets the link flapping detection interval.

The undo port link-flap interval command restores the default link flapping detection interval.

By default, the link flapping detection interval is 10s.

Format

port link-flap interval interval-value

undo port link-flap interval

Parameters

Parameter	Description	Value
interval interval-value	Specifies the link flapping detection interval.	The value is an integer that ranges from 5 to 60, in seconds. The default value is 10s.

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 configured interval 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 interval command multiple times in the same interface view, only the latest configuration takes effect.

Example

# Set the link flapping detection interval to 50s on GE0/0/1.

<HUAWEI> system-view
[HUAWEI] interface gigabitethernet 0/0/1
[HUAWEI-GigabitEthernet0/0/1] port link-flap interval 50