isis timer ldp-sync hold-down

Function

The isis timer ldp-sync hold-down command sets the interval during which an interface waits for creating an LDP session before setting up the IS-IS neighbor relationship.

The undo isis timer ldp-sync hold-down command restores the default setting.

By default, the interval is 10 seconds.

Format

isis timer ldp-sync hold-down value

undo isis timer ldp-sync hold-down

Parameters

Parameter	Description	Value
value	Specifies the interval during which an interface waits for creating an LDP session before setting up the IS-IS neighbor relationship.	The value is an integer ranging from 0 to 65535, in seconds.

Views

Interface view

Default Level

2: Configuration level

Usage Guidelines

Usage Scenario

On a network with both active and standby links, if the active link fails, traffic switches to a standby link. Therefore, the standby IS-IS route and backup LDP label switched path (LSP) along the standby link become reachable. After the active link recovers, its IS-IS route converges more rapidly than the LDP LSP. As a result, the IS-IS neighbor relationship is established earlier than the LDP session on the active link. Although traffic is directed over the IS-IS route to the active link, traffic fails to be forwarded because no LDP LSP is established.

To prevent the traffic forwarding failure, LDP and IS-IS synchronization can be configured. After the active link recovers from a physical fault, the IS-IS route for the active link is set to the Hold-down state, and the Hold-down timer starts. After an LDP session is established over the active link or the Hold-down timer expires, the IS-IS neighbor relationship starts to be established. This allows the LDP LSP and IS-IS route to go Up simultaneously. To set the Hold-down timer, run the isis timer ldp-sync hold-down command.

Prerequisites

The IS-IS process has been started using the isis enable command in the interface view.

Precautions

This command is circular in nature, and the latest configuration overrides the previous configurations.

Example

# Set the value of the Hold-down timer for VLANIF100 to 15 seconds, during which the interface waits for the establishment of an LDP session before setting up the IS-IS neighbor relationship.

<HUAWEI> system-view
[HUAWEI] interface vlanif 100
[HUAWEI-Vlanif100] isis enable 1
[HUAWEI-Vlanif100] isis timer ldp-sync hold-down 15

# Set the value of the Hold-down timer for GE0/0/1 to 15 seconds, during which the interface waits for the establishment of an LDP session before setting up the IS-IS neighbor relationship.

<HUAWEI> system-view
[HUAWEI] interface gigabitethernet 0/0/1
[HUAWEI-GigabitEthernet0/0/1] undo portswitch
[HUAWEI-GigabitEthernet0/0/1] isis enable 1
[HUAWEI-GigabitEthernet0/0/1] isis timer ldp-sync hold-down 15