mpls te switch-delay

Function

The mpls te switch-delay command sets the switching and deletion delays for a TE tunnel.

The undo mpls te switch-delay command restores the default settings.

By default, the switching delay is 5000 milliseconds and the deletion delay is 7000 milliseconds.

Format

mpls te switch-delay switch-time delete-delay delete-time

undo mpls te switch-delay switch-time delete-delay delete-time

Parameters

Parameter	Description	Value
switch-delay switch-time	Specifies the time period that the TE traffic is switched from the primary CR-LSP to the Modified CR-LSP.	The value is an integer that ranges from 0 to 600000, in milliseconds. The default value is 5000.
delete-delay delete-time	Specifies the delay for deleting the primary CR-LSP after the TE traffic is switched to a Modified CR-LSP.	The value is an integer that ranges from 0 to 600000, in milliseconds. The default value is 7000.

Views

MPLS view

Default Level

2: Configuration level

Usage Guidelines

Usage Scenario

MPLS TE uses the Make-Before-Break mechanism. When the attributes of an MPLS TE tunnel such as bandwidth and path change, a new CR-LSP with new attributes, also called Modified CR-LSP, must be established.

On the same modified CR-LSP, when a downstream LSR is too busy but the upstream LSR is not as busy, the Modified CR-LSP may go Up earlier on the upstream LSR than on the downstream LSR. The upstream LSR switches traffic to the Modified CR-LSP but the Modified CR-LSP is not Up on the downstream LSR. This causes a momentary traffic interruption. You can set a suitable switching delay time to avoid the traffic interruption.

If a modified CR-LSP fails, the failed node sends PathErr messages to its upstream LSRs and deletes the Modified CR-LSP, and traffic should be switched back to the primary CR-LSP. In applications, when detecting the fault, the upstream LSRs of the failed node are too occupied to forward the PathErr messages. This causes a traffic interruption on the failed node because the primary CR-LSP is deleted on the failed node. You can set a suitable deletion delay time to prevent the traffic interruption.

In a VPLS over MPLS TE scenario, you can configure TE FRR to improve network reliability. TE FRR protects links and nodes on an MPLS TE tunnel. If a link or node fails, TE FRR rapidly switches traffic to the protection path. However, traffic loss may occur during a traffic switchback if the delay for deleting the TE FRR protection path is too short. To prevent this situation, run the delete-delay delete-time command to configure an appropriate delay based on the number of VSIs on the MPLS TE tunnel:

30s if there are 2001 to 4000 VSIs
20s if there are 1001 to 2000 VSIs
10s if there are 501 to 1000 VSIs
7s if there are 1 to 500 VSIs

Prerequisites

MPLS TE has been enabled globally by running the mpls te command.

Example

# Set the switching delay of the TE tunnel to 3000 milliseconds and the deletion delay of the TE tunnel to 8000 milliseconds.

<HUAWEI> system-view
[HUAWEI] mpls
[HUAWEI-mpls] mpls te
[HUAWEI-mpls] mpls te switch-delay 3000 delete-delay 8000