dampening timer-interval

Function

The dampening timer-interval command configures BFD session flapping suppression timers.

The undo dampening timer-interval command restores the default configuration.

BFD session flapping suppression timers start by default.

The default initial, secondary, and maximum BFD session flapping suppression timer values are 2000 ms, 5000 ms, and 12000 ms, respectively.

Format

dampening timer-interval maximum maximum-milliseconds initial initial-milliseconds secondary secondary-milliseconds

undo dampening timer-interval [ maximum maximum-milliseconds initial initial-milliseconds secondary secondary-milliseconds ]

Parameters

Parameter	Description	Value
maximum maximum-milliseconds	Specifies a maximum BFD session flapping suppression timer value.	The value is an integer ranging from 1 to 3600000, in milliseconds. The default value is 12000.
initial initial-milliseconds	Specifies an initial BFD session flapping suppression timer value.	The value is an integer ranging from 1 to 3600000, in milliseconds. The default value is 2000.
secondary secondary-milliseconds	Specifies a secondary BFD session flapping suppression timer value.	The value is an integer ranging from 1 to 3600000, in milliseconds. The default value is 5000.

Views

BFD session view

Default Level

2: Configuration level

Usage Guidelines

Usage Scenario

If BFD detects link Down, services are switched. A penalty mechanism is provided to delay BFD session negotiation and prevent frequent service switchovers, protecting link resources and reducing link resource consumption.

To configure BFD session flapping suppression timers, run the dampening timer-interval command.

Prerequisites

BFD has been globally enabled using the bfd command in the system view.

Configuration Impact

After the dampening timer-interval command is run:

When a BFD session flaps for the first time, the initial BFD session flapping suppression timer starts. If the BFD session flaps again before the initial BFD session flapping suppression timer expires, BFD session renegotiation is triggered after the initial BFD session flapping suppression timer expires.
After the initial BFD session flapping suppression timer ends, the secondary BFD session flapping suppression timer starts. If the BFD session flaps before the secondary BFD session flapping suppression timer expires, BFD session renegotiation is triggered after the secondary BFD session flapping suppression timer expires. After that, the timer value is secondary-milliseconds x 2^(n-1), where n is the number of times that the secondary BFD session flapping suppression timer starts.
After the timer value of secondary-milliseconds x 2^(n-1) is greater than or equal to the value specified by maximum-milliseconds, the BFD session uses the value specified by maximum-milliseconds as a flapping delay three consecutive times. Then, the BFD session flapping delay is recalculated based on Step 1.

Precautions

The configured maximum BFD session flapping suppression timer value must be greater than the configured initial or secondary BFD session flapping suppression timer value. Otherwise, the configuration fails.

Do not configure both the dampening timer-interval and wtr commands. Otherwise, the BFD session recovery period becomes long.

Example

# Set a maximum, initial, and secondary BFD session flapping suppression timer values to 20000 ms, 1000 ms, and 3000 ms, respectively.

<HUAWEI> system-view

[HUAWEI] bfd

[HUAWEI-bfd] dampening timer-interval maximum 20000 initial 1000 secondary 3000