control-flap
Function
The control-flap command enables flapping control on the interface.
The undo control-flap command disables flapping control on the interface.
By default, flapping control is disabled.
Format
control-flap [ ipv6 ] [ suppress reuse ceiling decay-ok decay-ng ]
undo control-flap [ ipv6 ]
Parameters
| Parameter | Description | Value |
|---|---|---|
ipv6 |
Enables flapping control on the IPv6 interface. |
- |
suppress |
Specifies the threshold for suppressing the interface. When the suppress penalty value exceeds the suppress value, the interface is suppressed. |
The value ranges from 1 to 20000. The default value is 2000. This value must be greater than the reuse value and less than the ceiling value. |
reuse |
Specifies the threshold for reusing the interface. When an interface is Up and the suppress penalty value is less than the reuse value, the interface is no longer suppressed. When the interface is Down and the suppress penalty value is less than the reuse value, the interface is still suppressed. |
The value ranges from 1 to 20000. The default value is 750. The reuse value must be less than the suppress value. |
ceiling |
Specifies the maximum suppress penalty value of the interface. The suppress penalty value does not increase when it exceeds the ceiling value. |
This value ranges from 1001 to 20000. The default value is 6000. The ceiling value must be greater than the suppress value of the interface. |
decay-ok |
Specifies the half-life for decaying the penalty value when the interface is Up. |
The value ranges from 1 to 900, in seconds. The default value is 54. Generally, the decay-ok value should be set less than or equal to the decay-ng value. |
decay-ng |
Specifies the half-life for decaying the penalty value when the interface is Down. |
The value ranges from 1 to 900, in seconds. The default value is 54. Generally, the decay-ng value should be set greater than or equal to the decay-ok value. |
Views
Ethernet interface view, Ethernet sub-interface view, Eth-Trunk interface view, Eth-Trunk sub-interface view, Tunnel interface view, Dialer interface view
Usage Guidelines
Usage Scenario
Flapping control applies to reduce the adverse impact on the network stability caused by the change of interface status.
The initial penalty value is 0. The bigger the initial value, the poorer stability the interface. When an interface alternates between Up and Down, the penalty value changes. Each time an interface goes Down, the penalty value of the interface is increased by 1000. Each time the interface goes Up, the penalty value of the interface is calculated by the exponential backoff technology. When the penalty value reaches to a specified suppress value (suppress for short), the interface status is suppressed and not reported. The penalty value can be decreased by exponent (Half-life principle) as the time elapses. When the penalty value is decreased to a specified reuse value (reuse for short), the interface status is no longer suppressed and reported.
Half-life (decay-ok/decay-ng): an indicator that measures the decaying degrees of stability, indicating the time for the penalty value of the interface decays to the half.
Precautions
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 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. 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 1/0/0. Set the values of the suppress, reuse, ceiling, decay-ok, and decay-ng parameters to 2000, 750, 16000, 15, and 15, respectively.
<sysname> system-view
[sysname] interface GigabitEthernet 0/0/0
[sysname-GigabitEthernet0/0/0] control-flap 2000 750 16000 15 15