Bandwidth Management

Bandwidth Sizing Overview

NorthStar Controller can be configured to periodically compute a new planned bandwidth for each bandwidth sizing-enabled LSP based on aggregated LSP traffic statistics. NorthStar sends new planned bandwidth information to the NorthStar Path Computation Server (PCS) where the actual computation is done. The PCS determines, based on the new bandwidth requirements and the LSP bandwidth sizing parameters, whether it needs to provision the new planned bandwidth or not.

For bandwidth sizing to occur, you must:

• Enable NorthStar analytics

  NorthStar supports bandwidth sizing for all PCE-initiated and PCC-delegated LSPs for which it can obtain LSP statistics, either via Juniper Telemetry Interface (JTI), or SNMP collection (scheduled via the Task Scheduler). This means that you must enable/use NorthStar analytics, and confirm that NorthStar is receiving traffic from the LSPs.

• Configure PCE-initiated and PCC-delegated LSPs so their bandwidth sizing attribute is set to yes (bandwidth sizing enabled). LSPs without this setting are not sized.

• Create and schedule a bandwidth sizing task in the Task Scheduler, as described later in this topic.

Bandwidth Sizing on the PCS Versus Auto-Bandwidth on the PCC

Bandwidth sizing can be confused with auto-bandwidth. Auto-bandwidth is configured on the router. NorthStar supports auto-bandwidth by responding to instructions from the router regarding bandwidth changes. Table 1 summarizes the differences between auto-bandwidth and bandwidth sizing.

See NorthStar Controller Features Overview, Understanding the Behavior of Delegated Label-Switched Paths, and Creating Templates to Apply Attributes to PCE-Initiated Label-Switched Paths for more information about how NorthStar supports auto-bandwidth on the PCC.

Bandwidth Sizing-Enabled LSPs

Only bandwidth sizing-enabled LSPs are included in the re-computation of new planned bandwidths. When you add or modify an LSP, you must set the Bandwidth Sizing (yes/no) setting to yes to enable sizing.

At the same time, you also set values for the following parameters:

• Adjustment threshold (%)

  This setting controls the sensitivity of the automatic bandwidth adjustment. The new planned bandwidth is only considered if it differs from the existing bandwidth by the value of this setting or more.

• Minimum (planned) bandwidth

• Maximum (planned) bandwidth

  The minimum and maximum planned bandwidth values act as boundaries:

  • If the new planned bandwidth is greater than the maximum setting, NorthStar signals the LSP with the maximum bandwidth.

  • If the new planned bandwidth is less than the minimum setting, NorthStar signals the LSP with the minimum bandwidth.

  • If the new planned bandwidth falls in between the maximum and minimum settings, NorthStar signals the LSP with the new planned bandwidth.

• Minimum variation threshold

  This setting specifies the sensitivity of the automatic bandwidth adjustment when the new planned bandwidth is compared to the current planned bandwidth. The new planned bandwidth is only considered if the difference is greater than or equal to the value of this setting. Because it is not a percentage, this can be used to prevent small fluctuations from triggering unnecessary bandwidth changes.

  If both the adjustment threshold and the minimum variation threshold are greater than zero, both settings are taken into consideration. In that case, the new planned bandwidth is considered if:

  • The percentage difference is greater than or equal to the adjustment threshold, and,

  • The actual difference is greater than or equal to the minimum variation.

Adding a Bandwidth Sizing Task

The bandwidth sizing task periodically sends a new planned bandwidth for bandwidth sizing-enabled LSPs to the NorthStar PCS. The PCS determines whether it needs to provision the new planned bandwidth with a path that satisfies the new bandwidth requirement.

To schedule a bandwidth sizing task, navigate to Administration > Task Scheduler from the More Options menu.

1. Click Add in the upper right corner. The Create New Task window is displayed as shown in Figure 1.

   Figure 1: Create New Task Window

   Enter a name for the task, select Bandwidth Sizing from the Task Type drop-down menu, and click Next.

2. Select an aggregation statistics option from the drop-down menu shown in Figure 2.

   Figure 2: Bandwidth Sizing Task, Step 2

   The aggregation statistic works together with the task execution recurrence interval (the period of bandwidth adjustment) that you set up in the scheduling window. NorthStar aggregates the LSP traffic for the interval based on the aggregation statistic you select, and uses that information to calculate the new planned bandwidth. The options in the Aggregation Statistic drop-down menu are described in Table 2.

   Table 2: Bandwidth Sizing Aggregation Statistics Options

   Aggregation Statistic	Description
   80th, 90th, 95th, 99th Percentile	Aggregation is based on the selected percentile. The ‘X’ percentile is the value at which ‘X’ percent of all the samples taken in the previous sampling period lie at or below the calculated value. For bandwidth sizing, the newly-calculated bandwidth value is taken as the ‘X’ percentile of the samples in the immediately-preceding bandwidth sizing interval.
   Average	For each interval, the samples within that interval are averaged. If there are N samples for a particular interval, the result is the sum of all the sample values divided by N.
   Max	For each interval, the maximum of the sample values within that interval is used.

3. Click Next to proceed to the scheduling parameters. The Create New Task - Schedule window is displayed as shown in Figure 3. You must schedule the task to repeat at a specific interval from a minimum of 15 minutes to a maximum of one day. The default interval is one hour.

   Note:

   There is no per-LSP interval. The interval configured here applies to all LSPs for which bandwidth sizing is enabled.

   Figure 3: Bandwidth Sizing Task, Scheduling

4. Click Submit to complete the addition of the new collection task and add it to the Task List. Click a completed task in the list to display the results in the lower portion of the window. There are three tabs in the results window: Summary, Status, and History.

   Note:

   • You can have only one bandwidth sizing task per NorthStar server. If you attempt to add a second, the system will prompt you to approve overwriting the first one.

   • If the bandwidth sizing scheduled task does not result in published statistics for all the bandwidth sizing-enabled LSPs, see NorthStar Controller Troubleshooting Guide for troubleshooting tips.

   • LSPs for which traffic statistics are not available for a specified duration will not be resized if the bandwidth sizing task is scheduled to consider the statistics collected in the specified duration. This is because the task cannot differentiate between no traffic and zero bandwidth traffic.

Viewing LSP Statistics and Bandwidth

In the network information table (Tunnel tab), you can add optional columns related to bandwidth sizing by hovering over any column heading and clicking the down arrow that appears. Select Columns and click the check boxes to add columns for bandwidth sizing parameters as shown in Figure 4.

Figure 4: Bandwidth Sizing Columns

Once added, these columns display in the network information table the values of the parameters you configured for the bandwidth sizing-enabled LSPs.

You can view an LSP’s statistics and bandwidth in graphical form by right-clicking an LSP on the Tunnel tab of the network information table and selecting View LSP Traffic. An example of the display is shown in Figure 5.

Figure 5: Viewing LSP Traffic and Bandwidth

This example shows the actual LSP traffic (blue line) as well as the signaled (configured) bandwidth (green line). The hide bandwidth/show bandwidth button allows you to toggle back and forth between including and not including the bandwidth in the display.

Logs related to bandwidth sizing are stored in /opt/northstar/logs and include:

• bandwidth_sizing.log

• pcs.log

Using Bandwidth Sizing Together with Zero Bandwidth Mode

In Administration > System Settings, there is an option to enable zero bandwidth signaling. By default, this functionality is disabled. When enabled, NorthStar can optimize resource utilization more effectively and more aggressively. This is true, with or without bandwidth sizing, and it affects all PCE-initiated and PCC-delegated LSPs, regardless of whether they are bandwidth sizing-enabled or not.

When zero bandwidth signaling is enabled and NorthStar is receiving traffic statistics for bandwidth sizing-enabled LSPs, NorthStar does the following at the end of the bandwidth adjustment period:

• Computes the new planned bandwidth.

• Computes a new path that satisfies the new planned bandwidth.

• Updates the RSVP link utilization based on the new planned bandwidth and the new path.

• Provisions the new path with zero bandwidth as opposed to provisioning with the new planned bandwidth.

Container LSP Overview

A container LSP is a logical grouping of sub-LSPs that share the properties defined in the container. Container LSPs automatically add or remove sub-LSPs based on traffic statistics. This mitigates the difficulty of finding a single path large enough to accommodate a large bandwidth reservation.

Using container LSPs involves:

• Creating a container LSP from the network information table (Container LSP tab) on the topology page.

• Adding a container normalization task using the Task Scheduler.

• Viewing container LSPs, and their sub-LSPs in the network information table (Container LSP tab) on the Topology page.

Container LSPs on the PCS Versus TE++ LSPs on the PCC

Container LSPs are different from TE++ LSPs in ways that are important to understand. TE++ can only be configured on the router. NorthStar supports TE++ by responding to instructions from the router regarding the creation and deletion of sub-LSPs and the associated redistribution of bandwidth across the sub-LSPs. With container LSPs, NorthStar is doing the bandwidth computations and decision-making. Table 3 summarizes the differences between TE++ and container LSPs.

See NorthStar Controller Features Overview for more information about TE++ LSPs.

Creating a Container LSP

To create a container LSP, start in the network information table. On the tabs bar, click the plus sign (+) and select Container LSP from the drop-down menu as shown in Figure 6.

Figure 6: Adding the Container LSP Tab

Click Add at the bottom of the table to open the Add Container window.

Figure 7: Add Container Window, Properties Tab

The fields specific to container LSPs are described in Table 4. The remaining fields are the same as for creating regular LSPs.

Creating a Container Normalization Task

Use the Task Scheduler to enable periodic container LSP normalization. The container normalization task computes aggregated bandwidth for each container LSP and sends it to the NorthStar PCS. The PCS determines whether it needs to add or remove sub-LSPs belonging to the container LSP, based on the container’s new aggregated bandwidth.

To schedule a container normalization task, navigate to Administration > Task Scheduler from the More Options menu.

1. Click Add in the upper right corner. The Create New Task window is displayed as shown in Figure 8.

   Figure 8: Create New Task Window

   Enter a name for the task, select Container Normalization from the Task Type drop-down menu, and click Next.

2. Select an aggregation statistics option from the drop-down menu shown in Figure 9.

   Figure 9: Container Normalization Task, Step 2

   The aggregation statistic works together with the task execution recurrence interval that you will set up in the scheduling window, the same as it does for bandwidth sizing.

3. Click Next to proceed to the scheduling parameters which work just the same as for bandwidth sizing.

4. Click Submit to complete the addition of the new collection task and add it to the Task List. Click a completed task in the list to display the results in the lower portion of the window. There are three tabs in the results window: Summary, Status, and History.

   Note:

   • You can have only one container normalization task per NorthStar server. If you attempt to add a second, the system will prompt you to approve overwriting the first one.

   • Container LSPs for which traffic statistics are not available for a specified duration will not be normalized if the container normalization task is scheduled to consider the statistics collected in the specified duration. This is because the task cannot differentiate between no traffic and zero bandwidth traffic.

Viewing Container LSPs in the Network Information Table

The Container LSP tab is shown in Figure 10. You can add columns and filter the display in the usual ways. See Sorting and Filtering Options in the Network Information Table for more information.

Figure 10: Container LSP Tab in the Network Information Table

Right-click a row in the Container LSP tab to select either View Sub LSPs or View Traffic. Each of these options opens a new tab in the network information table displaying the requested information. Figure 11 shows the right-click options in the Container LSP tab.

Figure 11: Right-Click a Container LSP

When you select View Sub LSPs, a new tab in the network information table opens displaying the sub-LSPs and their parameters. In the list of sub-LSPs, you have all the display options normally available on the Tunnel tab. See Network Information Table Overview for more information. Figure 12 shows an example of a sub-LSPs tab in the network information table.

Figure 12: Sub-LSPs Tab in the Network Information Table

The sub-LSPs are also displayed in the Tunnel tab. The Container column (optionally displayed) identifies them as belonging to a container LSP. Figure 13 shows sub-LSPs in the Tunnel tab.

Figure 13: Viewing Sub-LSPs in the Tunnel Tab

When you right-click a row in the Container LSP tab and select View Traffic, a new tab opens in the network information table displaying the traffic for the container LSP.Figure 14 shows an example of the View Traffic tab.

Figure 14: View Traffic Tab in the Network Information Table

Logs related to container LSPs are stored in /opt/northstar/logs and include:

• container_lsp.log

• pcs.log