control-flap

Function

The control-flap command enables flapping control on an interface.

The undo control-flap command disables flapping control.

By default, flapping control is disabled on an interface.

Format

control-flap [ suppress reuse ceiling decay-ok decay-ng ]

undo control-flap

Parameters

Parameter	Description	Value
suppress	Input device actually suppress threshold value is 1000 times the actual value of the device. If the penalty value exceeds the interface suppressing threshold, the interface is suppressed. When the interface is suppressed, the outputs of the display interface, display interface brief, and display ip interface brief commands show that the protocol status of the interface remains DOWN(dampening suppressed) and does not change with the physical status.	The value ranges from 1 to 20000. The default value is 2000. This value must be greater than the reuse threshold and less than the ceiling threshold.
reuse	The value of the interface reuse threshold actually entered by the device is 1000 times the actual value of the device. If the penalty value falls below the interface reuse threshold, the interface is freed from suppression. When the interface is freed from suppression, the protocol status of the interface is in compliance with the actual status and does not remain Down (dampening suppressed).	The value ranges from 1 to 20000. The default value is 750. This value must be smaller than the suppress threshold of the interface.
ceiling	The maximum value of the interface suppression penalty value actually entered by the device is 1000 times the actual value of the device. The suppress penalty value stops increasing when it exceeds this value.	The value ranges from 1001 to 20000. The default value is 6000. This value must be greater than the suppress threshold of the interface.
decay-ok	Specifies the half life of the penalty value for an interface in the Up state. When an interface is Up, if the period since the end of the previous half life reaches the current half life, the penalty value decreases by half.	The value ranges from 1 to 900, in seconds. The default value is 54s.
decay-ng	Specifies the half life of the penalty value for an interface in the Down state. When the interface is Down, if the period since the end of the previous half life reaches the current half life, the penalty value decreases by half.	The value ranges from 1 to 900, in seconds. The default value is 54s.

Views

100GE interface view, 10GE interface view, 25GE interface view, 400GE interface view, 40GE interface view, 50GE interface view, Eth-Trunk interface view, FlexE sub-interface view, FlexE interface view, GE optical interface view, GE interface view, GE electrical interface view, Global VE sub-interface view, Global VE interface view, Tunnel interface view, VE sub-interface view, VE interface view, Sub-interface view, Management interface view

Default Level

2: Configuration level

Task Name and Operations

Task Name	Operations
interface-mgr	write

Usage Guidelines

Usage Scenario

Physical signal interference and incorrect link layer configuration may cause a device interface to alternate between Up and Down frequently, causing routing protocols to flap constantly. This greatly affects the device and network, and may cause a specific device to collapse and the network to be unavailable.

Flapping control applies to reduce the adverse impact on the network stability caused by interface status changes.

By default, the penalty value for interface suppression increases by 400 each time the interface goes Down, this value is 1000 times the actual value of the device.

For concepts and principles of interface flapping control, see interface flapping control.

decay-ok and decay-ng can be configured separately:

If an interface remains Up for a long period and the interface must be soon available when it is Up, decreasing decay-ok is recommended.
If an interface remains Down for a long period and the interface must be long suppressed when it is Down, increasing decay-ng is recommended.

Precautions

This command can be configured only on an interface working in Layer 3 mode.

To view the running status and statistics of control-flap on an interface, run the display control-flap command.

NULL interfaces and loopback interfaces do not support flapping control.

Directly connected interfaces that have static routes configured must both have control flapping enabled or disabled. If only one interface has control flapping enabled, the interface has to wait a period to go Up after it recovers. This hold-off time will cause the status of the two interfaces inconsistent, and packets are therefore discarded.

If the IP address of flapping control-enabled sub-interface is deleted when the sub-interface is in the suppressed state, the sub-interface will be always in the suppressed state.

Do not run the control-flap command on an interface that a Virtual Router Redundancy Protocol (VRRP) backup group tracks. If this command is run on the interface and the interface recovers from a fault, the interface goes Up after a specified delay time elapses. During the delay, the network-side route is unreachable, and the VRRP status changes from Backup to Master. User-side traffic directed to the interface will be discarded.

Example

# Enable flapping control on GE 0/1/0. Set the values of the suppress, reuse, ceiling, decay-ok, and decay-ng parameters to 2000, 750, 16000, 15, and 15, respectively.

<HUAWEI> system-view
[~HUAWEI] interface GigabitEthernet 0/1/0
[~HUAWEI-GigabitEthernet0/1/0] control-flap 2000 750 16000 15 15