Configure RSVP Soft Preemption

Soft preemption capability on unprotected adaptive LSPs (which is disabled by default) can be configured irrespective of its state (enable or disable).

Non-adaptive and/or FRR enabled LSPs cannot be configured with soft preemption capability. In this scenario, the LSP must be disabled first to configure soft preemption based on the policies, other changes also may be required, such as removing FRR.

All secondary paths configured on the LSP would be allowed to have soft preemption configured independently.

The following steps must be followed to configure soft preemption.

Configure the device.
```
device# configure
```
Enable the MPLS router.
```
device(config)# router mpls
```
Define the path.
```
device(config-router-mpls)# path sec
```
This defines the path with the name of "sec".
Configure the LSP
```
device(config-router-mpls-path-sec)# lsp test
```
This defines the LSP with a name of "test".
Set the egress router of the LSP.
```
device(config-router-mpls-lsp-test)# to 10.1.1.100
```
This designates the egress router IP address of 10.1.1.100.
Configures the LSP as adaptive.
```
device(config-rouoter-mpls-lsp-test)# adaptive
```
This enables the LSP to be dynamically modified.
Set the LSP to have preemption capability.
```
device(config-router-mpls-lsp-test)# soft-preemption
```
This sets the primary path.

Configure the secondary path.

device(config-router-mpls-lsp-test)# secondary-path sec

When FRR is configured, remove the FRR configuration.

device(config-router-mpls-lsp-test)# traffic-eng mean-rate 100

Configure the secondary path to be adaptive.

device(config-router-mpls-lsp-test-secpath-sec)# adaptive

For each secondary path, where soft preemption is intended to be configured, mark them adaptive, when already not adaptive, configure SOFT preemption.
```
device(config-router-mpls-lsp-test-secpath-sec)# soft-preemption
```
This sets the secondary path.

Enable the LSP.

device(config-router-mpls-lsp-test-secpath-sec)# enable
Connecting signaled LSP test

Example

The soft-preemption command enables soft preemption functionality. This command must be used on both, the primary and secondary paths.

device# configure 
device(config)# router mpls
device(config-router-mpls)# path sec
device(config-router-mpls-path-sec)# lsp test
device(config-router-mpls-lsp-test)# to 10.1.1.100
device(config-router-mpls-lsp-test)# traffic-eng mean-rate 100
device(config-router-mpls-lsp-test)# adaptive
device(config-router-mpls-lsp-test)# soft-preemption
device(config-router-mpls-lsp-test)# secondary-path sec
device(config-router-mpls-lsp-test)# traffic-eng mean-rate 100
device(config-router-mpls-lsp-test-secpath-sec)# adaptive
device(config-router-mpls-lsp-test-secpath-sec)# soft-preemption
device(config-router-mpls-lsp-test-secpath-sec)# enable