Optimize Energy Consumption by Shutting Down Unused PFEs

This topic describes how to optimize energy consumption by identifying and shutting down unused Packet Forwarding Engines (PFEs) on network devices.

Most network devices are designed with multiple Packet Forwarding Engines (PFEs) to support scalability and redundancy. However, the available forwarding capacity may not be always fully utilized. Unused PFEs continue to consume significant baseline power even when carrying little or no traffic.

The recommendation service analyzes device telemetry to identify unused PFEs that can be safely powered down and generates energy optimization recommendations for eligible PFEs. You can view the recommendations on the Device PFE Power Optimization recommendation card.

The recommendation identifies PFEs that are consistently unused and can be safely powered down without impacting traffic forwarding or redundancy.

Note:

Currently, the Device PFE Power Optimization recommendation is supported on the following platforms: PTX10016, PTX 10008, PTX10004, PTX10001-36MR.

A PFE is included in the Device PFE Power Optimization recommendation if the following conditions are met:

All ports mapped to the PFE show no traffic activity over a sustained observation window.
No ports associated with the PFE have an active physical link.
No production interfaces are operationally dependent on the PFE.
Redundancy requirements and failover capacity remain functional after disabling the PFE.

The Device PFE Power Optimization recommendation provides a list of unused PFEs, historical utilization trends, configlet-based actions to safely take the PFE offline, and benefits and risks associated with disabling the PFE. It also highlights the potential energy savings achievable by applying the recommendation.

Note:

The recommendation service runs once per day at around 3 AM UTC and uses the historical forwarding-plane telemetry and device configuration data available at that time. Changes in traffic demand or redundancy configuration are reflected after the next run.

By disabling unused PFEs, you can align the active forwarding capacity with actual demand. This helps reduce forwarding plane power consumption, lower cooling overhead, reduce operational cost, and improve overall data center sustainability.

To view unused PFEs and review recommended actions:

From the main menu, click Sustainability.
The Organization-Level Sustainability Dashboard appears.
Navigate to the Top Sites by Energy Consumption widget and click on a site with high energy consumption.
The Site-Level Sustainability Dashboard appears.
On the Site-Level Sustainability Dashboard, navigate to the Top Device by Energy Consumption widget and click on a device to investigate further.

The Device-Level Sustainability Dashboard appears.

Navigate to the Recommendation tab. The Device PFE Power Optimization recommendation card appears on the top of the page.

The card highlights the recommendation type, the count of PFEs identified as unused and safe to disable, and the potential energy savings you can achieve by applying this recommendation.

Note:

Recommendations are generated only if unused PFEs are identified on a device.
To generate energy optimization recommendations for unused PFEs atleast 24 hours of data is required.

Click the recommendation card to open the detailed recommendation panel.

Figure 1 shows a sample Device PFE Power Optimization recommendation panel.

Figure 1: Device PFE Power Optimization Sample Recommendation

The recommendation panel includes the following fields:

Table 1: Field Description
Field	Description
Recommendation Card	A high-level description of the recommendation type. Indicates the type of recommendation, the number of PFEs identified for applying the recommendation, and the potential energy savings achievable if the recommendation is applied.
Device PFE	PFE identified as unused and eligible for shutdown. Select a PFE from the drop-down list to view the recommended action. The drop-down displays entries in this format, `FPC <number>/PFE <number>`.
Description	Summary of why the PFE is identified as unused and why the action is recommended, referencing energy and traffic data points.
Actions	Provides step-by-step guidance and relevant configlet-based actions required to take the PFE offline without impacting the network traffic. Note: You must use the configlets in Apstra Data Center Director to apply configuration changes to the device. For more information on configlets, see Configlets in the Apstra Data Center Director User Guide.
Benefits	Displays quantified advantages, such as estimated power and cost savings and reduction in GHG emissions.
Risks	Highlights caveats such as potential dependencies, safety checks, and guardrails to consider before applying the suggested changes.
Timestamp	Indicates when the recommendation was generated and how long it is valid. Note: Recommendations are refreshed daily based on the latest device telemetry.

Apply the recommended action.

Use the configlets in Apstra Data Center Director to apply configuration changes to the device.

Configlets are custom configuration snippets that you can apply on a device through Apstra Data Center Director.
Note:
- Configuration changes made using configlets override Apstra-intended configuration.
- You may not get warnings for incorrect configurations pushed using configlets. Ensure you test and validate configlets in a dedicated validation environment before deploying them to the production environment.
- Passwords and other secret keys are not encrypted in configlets.
After applying the configuration changes to shutdown the PFE, return to the Device-Level Sustainability Dashboard to validate the results, such as reduction in device-level energy consumption and power cost.

Regularly review forwarding utilization trends, assess capacity, and ensure redundancy requirements remain satisfied after topology changes.

Note:
Changes to PFE states and traffic patterns may take up to 24 hours to reflect in the Sustainability Dashboards.

For chassis-level optimization, see Optimize Energy Consumption by Shutting Down Unused Line Cards.

For more granular, per-port energy optimization recommendation, see Optimize Energy Consumption by Shutting Down Unused Ports.