mpls te path-selection overload

Function

The mpls te path-selection overload command associates RSVP-LSP establishment with the IS-IS overload setting. This association allows CSPF to calculate paths excluding overloaded IS-IS nodes.

The undo mpls te path-selection command restores the default configuration.

By default, RSVP-LSP establishment is not associated with the IS-IS overload setting.

Format

mpls te path-selection overload

undo mpls te path-selection

Parameters

None

Views

MPLS view

Default Level

2: Configuration level

Task Name and Operations

Task Name	Operations
mpls-te	write

Usage Guidelines

Usage Scenario

An administrator can run the set-overload command to mark a node overloaded if the node is transmitting a large number of services or its CPU is overburdened. If there are overloaded nodes on an MPLS TE network, associate RSVP-LSP establishment with the IS-IS overload setting to ensure that RSVP-LSPs are established over paths excluding overloaded nodes. This configuration prevents overloaded nodes from being further burdened and improves RSVP-LSP reliability.

Prerequisites

CSPF has been enabled using the mpls te cspf command.

The route record has been enabled using the mpls te record-route command.

Configuration Impact

After the mpls te path-selection overload command is run, and an LSP passes through overloaded nodes, the following situations occur:

CSPF recalculates paths excluding overloaded nodes for established RSVP-LSPs.
NOTE: Traffic travels through an existing RSVP-LSP before a new RSVP-LSP is established. After the new RSVP-LSP is established, traffic switches to the new RSVP-LSP and the original RSVP-LSP is deleted. This traffic switchover is performed based on the make-before-break mechanism. Traffic is not dropped during the switchover.
CSPF calculates paths excluding overloaded nodes for new RSVP-LSPs.

Precautions

This configuration does not take effect on bypass or P2MP TE tunnels.

If the ingress or egress is marked overloaded, the mpls te path-selection overload command does not take effect. The established RSVP-LSPs associated with the ingress or egress will not be reestablished and new RSVP-LSPs associated with the ingress or egress will also not be established.

If a TE LSP uses the local device as a transit node before the set-overload command is run, the TE LSP is not torn down and re-established and still uses the local device as a transit node after the set-overload command is run; if the local device is restarted after the command is run and fast convergence is not configured on the ingress of the RSVP-LSP, TE LSP forwarding fails, and services are affected. Therefore, the mpls te path-selection overload command needs to be run on the ingress of the RSVP-LSP before the device is restarted.

Example

# Associate RSVP-LSP establishment with the IS-IS overload setting.

<HUAWEI> system-view
[~HUAWEI] mpls
[*HUAWEI-mpls] mpls te
[*HUAWEI-mpls] mpls te path-selection overload