suppress-flapping lsp-flood

Function

The suppress-flapping lsp-flood command configures a period for the system to delay LSP flooding during route flapping.

The suppress-flapping lsp-flood disable command restores the default configuration.

The undo suppress-flapping lsp-flood command restores the default configuration.

By default, if route flapping occurs, the device delays LSP flooding for 10s.

Format

suppress-flapping lsp-flood { disable | timer delay-interval [ threshold threshold-value ] }

undo suppress-flapping lsp-flood

Parameters

Parameter	Description	Value
timer delay-interval	Specifies a period for the system to delay LSP flooding during route flapping.	The value is an integer ranging from 1 to 600, in seconds.
threshold threshold-value	Specifies a route flapping threshold. If a route flaps for the specified number of times, LSP flooding is delayed.	The value is an integer ranging from 3 to 100, in times. The default value is 30,

Parameter

Description

Value

timer delay-interval

Specifies a period for the system to delay LSP flooding during route flapping.

The value is an integer ranging from 1 to 600, in seconds.

threshold threshold-value

Specifies a route flapping threshold. If a route flaps for the specified number of times, LSP flooding is delayed.

The value is an integer ranging from 3 to 100, in times. The default value is 30,

Views

IS-IS view

Default Level

2: Configuration level

Task Name and Operations

Task Name	Operations
isis	write

Usage Guidelines

Usage Scenario

On an IS-IS network, if the device receives an LSP with a routing information change, the Router floods LSPs to advertise the change. If routing information changes frequently and LSPs are flooded immediately, a lot of system resources will be consumed. To prevent this problem, run the suppress-flapping lsp-flood command to configure a period for the Router to delay LSP flooding during route flapping.

The flapping suppression process is as follows:

If the same LSP is flooded repeatedly within 3s, IS-IS records a flapping event and increases the flapping_count by 1. If the interval at which the system floods the same LSP is greater than 10s before flapping suppression takes effect, IS-IS clears the flapping_count. If the flapping_count is greater than threshold-value, flapping suppression takes effect.
During the flapping suppression period, IS-IS does not flood the same LSP, but the flapping_count may increase during this period. After the delay-interval elapses, IS-IS exits from flapping suppression and clears the flapping_count.
If an LSP is suppressed locally, the corresponding LSP on neighbors may age. To prevent this problem, a mechanism is provided. Specifically, if the Remaining Lifetime field in an LSP is less than or equal to delay-interval plus 60s, the LSP is not suppressed.

Prerequisites

An IS-IS process has been created and the IS-IS view has been displayed using the isis command.

Configuration Impact

If the device delays LSP flooding too long, other devices on the network cannot detect the route information change in time, slowing down route convergence.

Example

# Configure the device to delay flooding LSPs for 5s after a route flaps 10 times.

<HUAWEI> system-view
[~HUAWEI] isis
[*HUAWEI-isis-1] suppress-flapping lsp-flood timer 5 threshold 10