graceful-restart (MPLS-LDP view)

Function

The graceful-restart command enables LDP graceful restart (GR).

The undo graceful-restart command disables LDP GR.

By default, LDP GR is not enabled.

Format

graceful-restart

undo graceful-restart

Parameters

None

Views

MPLS-LDP view

Default Level

2: Configuration level

Task Name and Operations

Task Name	Operations
mpls-ldp	write

Usage Guidelines

Usage Scenario

In LDP GR mode, when an active/standby switchover or protocol restart occurs on the neighboring device of the local device, the local device (GR helper) helps the device (restarter) restart without interrupting packet forwarding.

If LDP GR is not enabled, during an active/standby switchover or upgrade, the neighboring device deletes the LSP because the session is in the Down state. As a result, traffic is interrupted in a short time. If LDP GR is enabled, the labels before and after an unexpected active/standby switchover or protocol restart can be consistent, and uninterrupted MPLS forwarding is ensured.

NOTE:

Currently, LDP supports only GR helper.

Prerequisites

MPLS and MPLS LDP have been enabled globally.

Implementation Procedure

When the graceful-restart command is run, the system displays the following message:

Warning: All the related sessions will be deleted if the operation is performed! Continue? [Y/N]:

To confirm to run the command, enter y.

Configuration Impact

After the graceful-restart command is run, when the peer performs an active/standby switchover, the local node functioning as the GR helper reserves forwarding entries within a specified period of time.

Precautions

Note:

Enabling or disabling GR causes the reestablishment of all LDP sessions.

Example

# Enable LDP GR.

<HUAWEI> system-view
[~HUAWEI] mpls
[*HUAWEI-mpls] quit
[*HUAWEI] mpls ldp
[*HUAWEI-mpls-ldp] graceful-restart