Cisco WAE Design 7.0.1 User Guide

Capacity Planning Optimization

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As demand grows on your network you need a way to address the additional traffic and congestion. To alleviate congestion, you can:

• Upgrade existing circuits by adding more capacity to them
• Augment these circuits with associated port circuits
• Add parallel circuits to existing circuits
• Specify new adjacencies between nodes that were not initially connected

To perform these planning optimization investigations, WAE Design includes a capacity planning optimization tool. The goal of a capacity planning optimization is to minimize the addition of any required capacity to be installed on the network. The capacity planning optimizer operates on both Layer 1 and Layer 3 network elements, as well as across failure sets, so you can use a combination of elements in a layered fashion to reach an acceptable solution to meet maximum utilization requirements.

Figure 23-1 shows an example of a network design before optimization, where extra demands were placed on the network. As a result, you can see congested interfaces in purple.

Figure 23-1 Design Before Optimization

Workflow

You can set optimization parameters to relieve network congestion and augment capacity. You start by defining a maximum utilization threshold for a specified set of interfaces and then layering additional options that operate on Layer 3, Layer 1, and across failure sets.

Note Some of the optimizer options are mutually exclusive; for example, if you tell the optimizer to create port circuits, it cannot create parallel circuits at the same time. Other options are complementary; for example, you can specify the creation of parallel circuits and new adjacencies together.

Step 1 Choose Tools > Capacity Planning Optimization.

Step 2 In the Layer 3 tab, define the maximum utilization threshold that you want to use for all interfaces in the network.

Step 3 Decide on the Layer 3 optimization options to use. (Options are described in Table 23-1 .)

• Specify the capacity parameters to use when upgrading circuits, creating port circuits, or creating parallel circuits.

Note You can specify both the capacity increment and the existing capacity of LAG circuits in tandem.

• Specify circuit upgrade parameters.

You can upgrade all existing circuits or a subset of these circuits. If you want to allow the upgrade of just certain circuits, indicate those circuits to be modified. This is useful if you want to limit your upgrades to a certain geographical location in the network.

To create new port circuits or parallel circuits, choose one of the following options:

– Create new port circuits (LAGs). In this case, the optimizer augments the existing circuits with associated port circuits (LAGs) with additional port circuits. The optimizer converts non-LAG circuits to LAGs.

– Create new parallel circuits. In this case, the optimizer creates new circuits that are parallel to existing circuits.

• Create new adjacencies.

By default, the optimizer does not create new adjacencies. If you specify a set of candidate nodes for it to use, the optimizer proposes new adjacencies. The optimizer restricts a new adjacency between the specified candidate nodes. For example, you might require that only core nodes be directly connected. In this case, specify only core nodes as your candidate nodes. Additionally, you can impose a limit on the maximum number of new adjacencies that the optimizer creates.

To create new adjacencies:

– Choose all the nodes in the table or just a subset of the nodes that you want to optimize.

– Specify the Maximum Number of New Adjacencies threshold.

Note You can apply the IGP metric to new adjacencies, but not to parallel circuits.

– Specify the IGP metric type for new interfaces, which can be either:

Decrement (default): The metric of new interfaces is equal to the shortest path minus the value specified in the metric option.

Fixed: The metric of new interfaces is equal to the value specified in the Fixed Metric field.

Step 4 (Optional) On the Layer 1 tab, check Create L1 Circuits. See Table 23-2 for the Layer 1 options and see Creating Layer 1 Circuits for more information.

Step 5 (Optional) On the Advanced tab, choose options to provide additional capacity planning and describe the cost for the various elements in your design.

Step 6 (Optional) On the Layer 3 tab, override the defaults for how circuits are tagged or for how new optimized plan files are named.

Step 7 Click OK to create the capacity planning optimization reports.

WAE Design routes the traffic and looks at the utilization threshold you specified, and any other optimization parameters you specified. After running an optimization, you can look at the summary report to see what the optimizer did to remove congestion. The key metric to look at is the Total Capacity Added (Mb/s).

Figure 23-2 shows the design after optimization using the parameters specified in Step 1. In this case, the optimizer proposes to set up two new adjacencies:

• One between Seattle (sea) and Houston (hst)
• One between Atlanta (alt) and Boston (bos)

Figure 23-2 Design After Optimization

Reports

The Reports window provides a summary report and a capacity upgrades table.

Summary Report Example

After running the optimization, the summary reports provide useful metrics at a glance. Using the previous design as an example with the default utilization threshold of 100%, the decrement interface metric type, and unbounded adjacencies, this report provides details on the:

• Total capacity added as a result of the optimization (in this example, 34832 Mb/s)
• Number of new adjacencies (in this example, 2)
• Number of upgraded circuits (in this example, 4)
• Number of new circuits (in this example, 2)
• Number of new ports (in this example, 36)
• Number of new port circuits (in this example, 28)
• Number of new L1 ports (in this example, 20)
• Number of new L1 circuits (in this example, 10)
• Number of new L1 circuit paths (in this example, 10)

Figure 23-3 After Optimization Summary Report Example

 

Capacity Upgrades Report Example

Click Capacity Upgrades for details on how the optimizer upgraded circuits. Using the previous optimized design as an example and using the default utilization threshold of 100%, the decrement interface metric type, and unbounded adjacencies, this report provides details on the six circuit upgrades that it suggests to meet your optimization parameters.

Figure 23-4 After Optimization Capacity Upgrades Report Example

 

In this example, out of the six upgrades listed, there were two new port circuits created for each upgraded circuit.

Layer 3 Optimization Options

You have several Layer 3 options for capacity planning. These parameters tell the optimizer what your preferences are in terms of utilization thresholds, capacity increments, and whether to upgrade existing circuits, create new adjacencies between nodes, create port circuits, or create parallel circuits.

Parallel Circuits Design Example

Figure 23-5 shows the first design in this chapter with parallel circuits added to increase capacity. In this case, the optimizer proposes five sets of parallel circuits:

• One between Houston (hst) and Los Angeles (lax)
• One between Los Angeles (lax) and San Jose (sjc)
• One between San Jose (sjc) and Seattle (sea)
• One between Boston (bos) and New York City (nyc)
• One between Atlanta (atl) and Washington, D.C. (wdc)

Because the utilization threshold was set to 100%, utilizations over 90% (shown in red) are acceptable solutions.

Figure 23-5 Adding Parallel Circuits to Increase Capacity

 

Layer 1 Optimization Options

The Layer 1 options tell the optimizer to create new L1 circuits.

Advanced Optimization Options

Use the advanced options to:

• Choose whether to optimize for capacity or cost.
• Define what failure scenarios to consider.

Step 1 In the Capacity Planning Optimization tool, click the Advanced tab.

Step 2 Click one of the following radio buttons:

• Minimize Capacity—(Default) Minimizes the capacity that is added to your network.
• Minimize Cost—Runs the optimization with the objective of reducing the overall cost when adding new capacity. Click Insert to manually enter a cost unit for capacity, L3 and L1 ports, and the feasibility limit. Alternately, click Import to import cost values from a file.

When you run an optimization, the tool generates a report on the overall cost—including the cost of the added ports—and recommends the most cost-efficient solution.

Step 3 In the Failure Sets area, choose options that you want the optimizer to consider (circuits, nodes, sites, and so on). Entries appear dimmed if they are not available in your design plan.

Step 4 (Optional) Specify the maximum number of threads. By default, the optimizer tries to set this value to the optimal number of threads based on the available cores.

Step 5 Click OK.

This action creates the capacity planning optimization report showing the results of the increased capacity. The optimizer takes into account whether it makes sense to upgrade existing circuits or set up new adjacencies, and considers capacity increments, cost options, and feasibility limits.