mpls te soft-preemption (Tunnel interface view)

Function

The mpls te soft-preemption command enables the soft preemption function in the view of a specified tunnel interface on the ingress.

The undo mpls te soft-preemption command disables the soft preemption function the view of a specified tunnel interface on the ingress. If tunnel soft preemption is enabled in the MPLS view, the global configuration takes effect on the local tunnel interface on the ingress.

The mpls te soft-preemption block command disables the soft preemption function for tunnels on the ingress.

The undo mpls te soft-preemption block command unblocks the soft preemption function for tunnels on the ingress. If tunnel soft preemption is enabled in the MPLS view, the global configuration is inherited for tunnels.

By default, if soft preemption is disabled in the MPLS view, a local tunnel is incapable of this function. If soft preemption is enabled in the MPLS view, the local tunnel is capable of this function.

Format

mpls te soft-preemption

mpls te soft-preemption block

undo mpls te soft-preemption

undo mpls te soft-preemption block

Parameters

None

Views

Tunnel interface view

Default Level

2: Configuration level

Task Name and Operations

Task Name	Operations
mpls-te	write

Usage Guidelines

Usage Scenario

The setup and holding priorities and the preemption function are configured to allow TE tunnels to be established preferentially to transmit important services, preventing random resource competition during tunnel establishment.

If there is no path meeting the bandwidth requirement of a desired tunnel, a device can tear down an established tunnel and use bandwidth resources assigned to that tunnel to establish a desired tunnel. This is called preemption. The following preemption modes are supported:

Hard preemption: A tunnel with a higher setup priority can preempt resources assigned to a tunnel with a lower holding priority. Consequently, some traffic is dropped on the tunnel with a lower holding priority during the hard preemption process.
Soft preemption: After a tunnel with a higher setup priority preempts the bandwidth of a tunnel with a lower holding priority, the soft preemption function retains the tunnel with a lower holding priority for a specified period of time. If the ingress finds a better path for this tunnel after the time elapses, the ingress uses the make-before-break (MBB) mechanism to reestablish the tunnel over the new path. If the ingress fails to find a better path after the time elapses, the tunnel goes Down.
To enable soft preemption, run the mpls te soft-preemption command.

Prerequisites

MPLS TE has been configured as a tunnel protocol using the tunnel-protocol mpls te command.

RSVP-TE has been configured using the mpls te signal-protocol rsvp-te command.

Configuration Impact

The priority and preemption attributes are used in conjunction to determine resource preemption among tunnels. If multiple tunnels are to be established, tunnels with higher setup priorities can be established by preempting resources. If resources, such as bandwidth, are insufficient, a tunnel with a higher setup priority can preempt resources of an established tunnel with a lower holding priority.

Example

# Disable soft preemption on Tunnel1.

<HUAWEI> system-view
[~HUAWEI] mpls
[*HUAWEI-mpls] mpls te
[*HUAWEI-mpls] quit
[*HUAWEI] interface tunnel 1
[*HUAWEI-Tunnel1] tunnel-protocol mpls te
[*HUAWEI-Tunnel1] mpls te soft-preemption block

# Enable soft preemption on Tunnel1.

<HUAWEI> system-view
[~HUAWEI] mpls
[*HUAWEI-mpls] mpls te
[*HUAWEI-mpls] quit
[*HUAWEI] interface tunnel 1
[*HUAWEI-Tunnel1] tunnel-protocol mpls te
[*HUAWEI-Tunnel1] mpls te soft-preemption