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Path Analysis Window

 

For many large networks, when a tunnel is rerouted due to a network failure, the new path remains in use even when the network failure is resolved. Thus, after an extended period of time, a suboptimal set of paths might evolve in the network.

To re-establish an optimal set of paths for a network in this situation, the NorthStar Controller has the Path Analysis feature.

To use the Path Analysis feature, you must first have a network project loaded. The NorthStar Controller finds the optimal placement of tunnels using the current set of nodes and links in the network.

From the Juniper NorthStar Planner window, select Application > Path Analysis. The Path Analysis window is displayed as shown in Figure 1.

Figure 1: Path Analysis Window
Path Analysis Window

Table 1 lists the fields in the Path Analysis window.

Table 1: Path Analysis Window Fields

Field

Description

Name

The name of the tunnel.

Node A

The name or IP address of the ingress node.

Node Z

The name or IP address of the egress node.

BW

The bandwidth of the tunnel.

Orig AW

The original administrative weight.

Best AW

The best possible administrative weight for the tunnel if there are no other tunnels in the network.

Best AW Gain

The difference between the Orig AW and the Best AW.

New AW

The optimal administrative weight for the tunnel, taking into account the other tunnels in the network.

AW Gain

The difference between the Orig AW and the New AW.

Orig Path

The original path of the tunnel.

Best Path

The best possible path of the tunnel if there are no other tunnels in the network.

New Path

The optimal path for the tunnel, taking into account the other tunnels in the network.

Type

The Type field is used by the NorthStar Controller to identify properties of the LSP such as PCC delegated, PCC initiated, or externally-controlled.

To optimize all LSPs displayed in the Path Analysis table, select Optimize > Optimize All. To optimize selected LSPs displayed in the Path Analysis table, select Optimize > Optimize Selected. To highlight the selected LSPs in the topology map and display the Paths window, click View Paths. In the Paths window, you can toggle the Highlight: All Paths or Highlight None selection.

After performing path analysis, select View Changes > View Summary to display a summary of the path analysis results. Select View Changes > View Link Changes to display a list of link changes. Select View Changes > View LSP Changes to display a list of path changes.

To see the options that control how path analysis operates, select Options. The Path Analysis Options dialog box is displayed as shown in Figure 2.

Figure 2: Path Analysis Options Dialog Box
Path Analysis Options Dialog
Box

In the Path Analysis Options window, you can set the Placement Order options for the Path Analysis feature to use the following:

PreemptionThis option is always disabled for Path Analysis and always enabled for Path Optimization. This is for display purposes only to distinguish the optimization behavior between the two methods.
Follow EROThe path follows the Explicit Route Objects (EROs). This option can be enabled or disabled for Path Analysis. It is always enabled for Path Optimization.
Placement OrderThe following menu items are available:
High-Priority First: Input OrderPlace high-priority tunnels before low-priority tunnels. For tunnels with the same priority, sort by the order of the tunnels in the input file.
High-Priority First: ScramblePlace high-priority tunnels before low-priority tunnels. For tunnels with the same priority, sort randomly.
High-Priority, High BW Tunnels First: Input OrderPlace high-priority tunnels before low-priority tunnels. For tunnels with the same priority, place high-bandwidth tunnels before low-bandwidth tunnels. For tunnels with the same priority and bandwidth, sort by the order of the tunnels in the input file.
High-Priority, High BW Tunnels First: ScramblePlace high-priority tunnels before low-priority tunnels. For tunnels with the same priority, place high-bandwidth tunnels before low-bandwidth tunnels. For tunnels with the same priority and bandwidth, sort randomly.
Scramble RandomlySort all tunnels together randomly and place them accordingly.
Low Bandwidth Tunnels First: ScramblePlace low-bandwidth tunnels before high-bandwidth tunnels. Among same-bandwidth tunnels, sort randomly. If there are multiple links between two nodes, fewer tunnels can usually be routed if this option is used. It is provided for worst-case study.
High Bandwidth Tunnels First: ScramblePlace high-bandwidth tunnels before low-bandwidth tunnels. Among same-bandwidth tunnels, sort randomly.
Input OrderRoute tunnels only by the order in the input file.
Note

The path analysis Placement Order option is set by selecting Tools > Options and then selecting Path Placement. Selecting the placement order from the drop-down menu in the Path Analysis Options dialog box has no effect.