mpls te switch-delay

Function

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

undo mpls te switch-delay command restores the default interval.

By default, the switching delay is 5000 ms and deletion delay is 20, 000 ms.

Format

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

undo mpls te switch-delay

Parameters

Parameter	Description	Value
switch-time	Specifies the delay time for switching TE traffic from a primary CR-LSP to a Modified CR-LSP.	The value is an integer ranging from 0 to 600000, in milliseconds. By default, the value is 5000.
delete-delay delete-time	Specifies the delay time for deleting a primary CR-LSP after TE traffic has switched to a Modified CR-LSP.	The value is an integer ranging from 0 to 600000, in milliseconds. By default, the value is 20000.

Parameter

Description

Value

switch-time

Specifies the delay time for switching TE traffic from a primary CR-LSP to a Modified CR-LSP.

The value is an integer ranging from 0 to 600000, in milliseconds. By default, the value is 5000.

delete-delay delete-time

Specifies the delay time for deleting a primary CR-LSP after TE traffic has switched to a Modified CR-LSP.

The value is an integer ranging from 0 to 600000, in milliseconds. By default, the value is 20000.

Views

MPLS view

Default Level

2: Configuration level

Task Name and Operations

Task Name	Operations
mpls-te	write

Usage Guidelines

Usage Scenario

MPLS TE adopts the make-before-break mechanism. When an MPLS TE tunnel's attributes (such as bandwidth and path) change, a new CR-LSP (also called modified CR-LSP) with the new attributes needs to be established. With make-before-break, the new CR-LSP is established before the original CR-LSP (also called the primary CR-LSP) is torn down, minimizing data loss during a traffic switchover to the new CR-LSP.

In actual applications, if the traffic volume greatly differs on an upstream node and a downstream node, the forwarding entries may be inconsistent on the two nodes. When this is the case, traffic may be interrupted for a short time.

To prevent this issue, run the mpls te switch-delay command on the tunnel ingress to set switching and deletion delays. Then, after a new CR-LSP is established, the system waits for the specified switching delay to expire before switching traffic to the new CR-LSP. After the switchover is complete, the system waits for the specified deletion delay to expire before tearing down the original primary CR-LSP.

For example:

The traffic on the upstream node of a TE tunnel is light but heavy on the downstream node. In such a scenario, the upstream node may switch traffic to the modified CR-LSP before forwarding entries are updated completely on the downstream node. When this is the case, traffic will be interrupted for a short time after being switched to the modified CR-LSP. To resolve this issue, run the mpls te switch-delay command to adjust the switching and deletion delays.

Prerequisites

MPLS TE has been enabled globally using the mpls te command.

Configuration Impact

Setting an appropriate switching or deletion delay time is recommended. A large value may cause other CR-LSPs to fail to be established when the number of CR-LSPs approaches to the upper limit or route flapping occurs.

Precautions

During the switching or deletion delay time, changing or deleting a set delay time does not take effect.

Example

# Set the switching delay to 3000 milliseconds and the deletion delay to 8000 milliseconds for an MPLS TE tunnel.

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