Cisco Crosswork Network Controller 7.2 Traffic Engineering and Optimization

PDF

Cisco Crosswork Network Controller 7.2 Traffic Engineering and Optimization

Create dynamic SR-MPLS policies based on optimization intent

Updated: August 4, 2025

Want to summarize with AI?

Log in

Use this task to create dynamic SR-MPLS policies that optimize network traffic paths according to user-defined metrics and constraints.

SR-PCE computes a path for the policy based on metrics and path constraints (affinities or disjointness) defined by the user. A user can select from three metrics to minimize in-path computation: IGP, TE, or latency. SR-PCE automatically re-optimizes the path as necessary, responding to topology changes. When a link or interface fails, the network locates an alternate path that meets the criteria specified in the policy and raises an alarm. If no valid path is found, an alarm occurs, and the packets are dropped.

To create SR-MPLS policies with a dynamic path, complete these steps:

Procedure

1.

Choose Services & Traffic Engineering > Traffic Engineering > SR-MPLS.

2.

Click Create > PCE Init . To provision a PCC-initiated policy using NSO via the Crosswork Network Controller UI, see Create SR-TE policies (PCC-initiated).

3.

Under Policy details , enter or select the required SR-MPLS policy values. Hover over the Field Help icon icon to view a description of each field.

Note

If you have set up device groups, you can select the device group from the Device groups drop-down list. Navigate and zoom in on the topology map to choose the device for headend or endpoint selection.

4.

Under Policy path, click Dynamic path and enter a path name.

5.

Under Optimization objective, select the metric you want to minimize.

6.

Define any applicable constraints or specify any required disjointness.

Affinity considerations

  • Affinity constraints and disjointness cannot be configured on the same SR-MPLS policy. No more than two SR-MPLS policies can exist in any disjoint group or subgroup. The configuration will not be allowed during Preview.

  • If there are existing SR-MPLS policies in a disjoint group, all policies from that group are displayed during Preview.

  • If SRLG exclusion constraints are defined for a Flexible Algorithm, any links belonging to the specified excluded SRLGs will be automatically filtered out from the IGP routing calculations, optimizing alternate paths by considering only the available links. For more information, see Configure and visualize flexible algorithm SRLG exclusion.

7.

Under Segments , select whether to use protected segments when available. Enter any applicable SID constraint. Crosswork Network Controller will try to find a path with this SID. If it cannot find a path with the SID constraint, the provisioned policy remains operationally down until the conditions are met.

SID information

  • Flexible Algorithm—The values correspond to the Flexible Algorithm defined on the device. Cisco IOS XR enforces the 128-255 range.

  • Algorithm 0—This is a Shortest Path First (SPF) algorithm based on link metric. The Interior Gateway Protocol (IGP) computes this shortest path.

  • Algorithm 1—This is a Strict Shortest Path First (SSPF) algorithm based on link metric. It is identical to algorithm 0, but requires all nodes along the path to honor the SPF routing decision. Local policy does not alter the forwarding decision. For example, a packet is not forwarded through locally engineered path.
8.

Click Preview to highlight the path on the map. Click Provision to activate the policy on the network.

9.

Validate the SR-MPLS policy creation.

  1. Confirm that the new SR-MPLS policy appears in the Traffic engineering table. Select the policy to highlight it on the map.

    Note
    It may take time for the newly provisioned SR-MPLS policy to appear in the table, depending on network size and performance. The Traffic engineering table refreshes every 30 seconds.

  2. View and confirm the new SR-MPLS policy details. In the Traffic engineering table, click More icon and select View details.