Cisco Crosswork Planning Design 7.2.x User Guide

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Cisco Crosswork Planning Design 7.2.x User Guide

LSP loadshare optimization

Updated: August 14, 2026

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Explains how LSP loadshare optimization automates the balancing of traffic across parallel LSPs and helps prevent congestion in the network.

A LSP loadshare optimization is a Cisco Crosswork Planning tool that

  • automates the process of finding and setting the most favorable loadshare ratios across parallel LSPs

  • includes only interfaces that use parallel LSPs in the optimization process, and

  • allows you to limit parallel LSP interfaces to only those on which you want to drive down the maximum utilization.

After completing the operation, the system tags the LSPs with LSPLoadshare and generates a report. The report includes:

  • The number of LSPs and interfaces affected

  • The number of bins used

  • The resulting maximum interface utilization

  • The number of interfaces exceeding the specified utilization threshold

Run LSP loadshare optimization

Use this task to optimize LSP loadshare settings to improve traffic distribution and minimize overutilization in your network.

Procedure

  1. Open the plan file (refer to Open plan files). It opens in the Network Design page.

    From the toolbar, choose Actions > Tools > LSP optimization > LSP loadshare optimization.

    Alternatively, choose Preset workflows > Perform optimization, select LSP Optimization as the optimization type, select LSP loadshare optimization from the drop-down list, and click Launch.

  2. Choose the LSPs on which you want to run the optimizer and click Next.

    It sets the loadshare setting between the selected parallel LSPs in the network. Parallel LSPs are those with the same source and destination nodes. By default, none of the LSPs are selected. However, you can also choose a subset or all the LSPs to optimize for load sharing purposes.

    The optimizer does not set a loadshare value of 0 on LSPs.

  3. Choose the interfaces on which you want to drive down utilization and click Next.

    • If you select all the interfaces, the optimizer uses all interfaces in the network model.

    • Choose only those interfaces of interest on which to drive down the maximum utilization.

  4. Specify the relevant optimization settings. For field descriptions, refer to LSP loadshare optimization settings.

    Figure 1. LSP loadshare optimization options
    LSP loadshare optimization options

  5. Select which traffic level to optimize.

  6. (Optional) In the Tag changed LSPs field, override the defaults for how LSPs are tagged (LSPLoadshare).

  7. On the Run Settings page, choose whether to execute the task now or schedule it for a later time. Choose one of these Execute options:

    • Now: Choose this option to execute the job immediately. The tool runs and changes are applied to the network model immediately. A summary report appears. You can access the report any time later using Actions > Reports > Generated reports option.

    • As a scheduled job: Choose this option to execute the task as an asynchronous job. Set these options:

      • Priority: Select the priority of the task.

      • Engine profiles: Select the engine profile as needed. This section lists all the available asynchronous engine profiles.

      • Schedule: Set the time at which you want to run the tool.

      The tool runs at the scheduled time using the selected engine profile. You can track the status of the job at any time using the Job Manager page (from the main menu, choose Job Manager). Once the job completes, import the output plan file into user space to visualize it. For more information, refer to Access output plan files from job manager.

      Note
      Ensure that you save the plan file before you schedule the job. Any unsaved changes in the plan file are not considered when you run the tool as a scheduled job.

  8. (Optional) If you want to display the result in a new plan file, specify a name for the new plan file in the Display results section.

    In the previous step:

    • If you have selected to run the task immediately, by default, the changes are applied on the current plan file. If you want to display the results in a new file, select the Display results in a new plan file check box and enter the name of the new plan file.

    • If you have scheduled the task to run at a later time, by default, the results are displayed in the Plan-file-1. Update the name, if required.

  9. Submit your changes.

LSP loadshare optimization settings

This table describes the available parameters for LSP loadshare optimization which controls how traffic is distributed among LSPs.
Table 1. LSP loadshare optimization settings

Field

Description

Minimize max interface util

Minimizes the maximum interface utilization over all interfaces on the LSP routes. Cisco Crosswork Planning tries to minimize the number of loadshare parameter changes required to do so.

Minimize number of interfaces with util >___%

Minimizes the number of interfaces that have a utilization greater than the specified value. This is a looser constraint than minimizing the maximum interface utilization. Therefore, Cisco Crosswork Planning has the opportunity to modify as few loadshare values as possible, thus reducing the amount of reconfiguration required.

Number of flow bins

Routers typically cannot divide flows arbitrarily between parallel LSPs, but instead allocate them to a fixed number of “bins” of approximately equal size. The bins are then divided between the parallel LSPs. This option lets you specify the total number of bins, which in turn places a constraint on the traffic division.

Traffic level

Specifies the traffic level to use in the optimization.

Tag changed LSPs

Specifies a tag for any changed LSPs. By default, the optimizer tags upgraded circuits with the label LSPLoadshare.

Minimization strategies for interface utilization

This is an example to apply minimization strategies and adjust Loadshare parameters to a sample plan file. The tags are applied on the optimized LSPs only, resulting in lower interface utilization and an updated plan file for further analysis.

The base plan for this example, Acme_Network, contains two sets of parallel LSPs, each with a Loadshare value of 1 and each using strict hops on named paths to reach its destination. All of these LSPs have a Traff sim of 3000 Mbps. The interfaces to which these LSPs filter all have a Traff sim value of 3000 Mbps, except for sjc-to-okc, which has 6000 Mbps of simulated traffic (Figure 1).

Using the Acme_Network plan file, if you minimize the maximum interface utilization across all LSPs, all four Loadshare parameters change, and the maximum interface utilization is 40% (Figure 2). The default LSP tags are used, thus naming the tags as LSPLoadshare. If you select the Display results in a new plan file option, then a new plan file Plan-file-1.pln is created by default.

Figure 2. Example Acme network before LSP loadshare optimization
Example network before LSP loadshare optimization
Figure 3. Example Acme network after minimizing maximum interface utilization

Traffic allocation minimization for LSP bins

This example describes how traffic allocation minimization uses bins to approximate optimal splits when a node must route traffic over multiple LSPs.
In this example, consider a node that uses a maximum of 32 bins, and the optimal traffic allocation is 45% of the traffic through LSP A and 55% of the traffic through LSP B. The node that sources these two LSPs, however, cannot do this exact split.

The optimization divides the traffic into 32 bins, each with the same amount of traffic in them. So, each bin has 3.125% of the traffic (100% of the traffic divided by 32). The optimization also determines how the node should split the traffic. In this case, the split is to give 43.75% (which is 14 bins of 3.125% each) to LSP A and 56.25% (which is 18 bins of 3.125% each) to LSP B. Thus, it optimizes and distributes 32 (14+18) bins of traffic. This is as close as possible to the optimal 45%/55% split using 32 bins.