There are several optimization parameters that you can set to relieve network congestion and augment capacity, depending on your goals. It starts with 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 that you can choose are mutually exclusive, for example, if you tell the optimizer to create port circuits, then it cannot create parallel circuits at the same time, and vice-versa, while other options are complementary. For example, you can specify the creation of parallel circuits and new adjacencies together.
Step 1 Navigate to Tools > Capacity Planning Optimization. By default, the optimizer presents you with Layer 3 optimization options.
Figure 27-2 Capacity Planning Optimization Tool
Step 2 In the Layer 3 tab, define the maximum utilization threshold that you want to use for all interfaces in the network. By default, the optimizer sets this threshold at 100% congestion.
Step 3 Decide on the Layer 3 optimization options to use. See Table 27-1 for all of the Layer 3 options and field descriptions.
- 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.
– Set the Capacity Increment (the default is 100000 Mb/s).
– Use the capacity of existing LAG Members. This tells the optimizer to copy and use the existing (same capacity) as those LAG members in the design when it creates new port circuits.
- Specify Circuit Upgrade parameters.
You can upgrade all existing circuits or a subset of these circuits (the default is to upgrade all circuits). If you want to allow the upgrade of just certain circuits, then indicate those circuits to be modified. This is useful if you want to limit your upgrades to a certain geographical location in the network.
Note You can create new port circuits or new parallel circuits, but not both at the same time.
To create new port circuits or parallel circuits, select 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.
By default, the optimizer does not create new adjacencies. If you specify a set of candidate nodes for it to use, then 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:
– Select 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, click Create L1 Circuits. See Table 27-2 for the Layer 1 options and see Creating Layer 1 Circuits for more information.
Step 5 (Optional) On the Failure Set tab, select one or more options to provide additional capacity planning failure options. See Adding Failure Set Options for more information.
Step 6 (Optional) Override the defaults for how circuits are tagged or for how new optimized plan files are named.
Step 7 Click OK. This runs the optimizer and creates the capacity planning optimization reports.
WAE Design routes all 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) number after the Options section of the report.
Figure 27-3 shows the design after optimization using the parameters specified in Figure 27-2. 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 27-3 Design After Optimization
Failure Set Optimization Options
When performing a capacity planning optimization, it is often the case that you need to consider failure scenarios. Under failure events, the optimizer reroutes demands, which leads to network congestion. By default, the optimizer does not take these failures into consideration. If you specify a failure set, then the optimizer considers all of the failures with the failure set and proposes capacity upgrades so that there is no congestion under any specified failure event. This enables you to plan for more robust networks.
This is similar to running a worst-case simulation analysis in that it adds more fail-safe scenarios to your capacity plan.
Note You can use the Failure Set options on top of the Layer 1 and Layer 3 options to create a multi-layer design and a more robust network.
Adding Failure Set Options
Step 1 In the Capacity Planning Optimization tool, select the Failure Set tab.
Step 2 Select one or more failure sets that you want the optimizer to consider:
– Port Circuits
– L1 Links
– L1 Nodes
– L1 Ports
Certain entries appear grayed out if they are not available in your design plan. In the next example, the plan file does not include SRLGs or External Endpoint Members.
Step 3 (Optional) Specify the Maximum number of threads.
By default, the optimizer attempts to set this value to the optimal number of threads based on the available cores.
Step 4 Click OK.
This action runs the optimizer and creates the capacity planning optimization report showing the results of the increased capacity. You can view additional capacity information on the Capacity Upgrades report.