Switch CPU Utilization Alert

The Switch CPU Utilization alert is generated when the average CPU utilization on a switch exceeds the configured threshold for a specified duration. High CPU utilization may indicate excessive control-plane processing, protocol activity, or abnormal system behavior.

Sustained high CPU usage can impact device responsiveness, delay management operations, and affect control-plane protocols running on the switch.

Figure 1: Switch CPU Utilization Sample Image

Alert Triggering and Clearing Conditions

  • Triggering Condition—The alert is triggered when the average CPU utilization exceeds the configured threshold (for example, 10%) for a defined time window.

  • Clearing Condition— The alert automatically clears when the CPU utilization drops below the configured threshold and stabilizes.

Alert Behavior

When an Switch CPU Utilization alert is triggered:

  • HPE Aruba Networking Central analyzes CPU utilization trends and system processes.

  • Impact assessment is performed to determine whether the issue affects clients, access points, gateways, or switch operations.

  • Diagnostic insights are displayed through Summary, Impact, Action, and History cards.

  • Root cause analysis is performed to identify possible causes of high CPU consumption.

Summary Card

The Summary card provides key alert information including:

  • Affected switch name.

  • Average CPU utilization.

  • First occurred and last occurred timestamps.

  • Duration of the alert.

  • Number of occurrences.

  • Alert priority and a;ert scope (device level)

    This information helps determine the severity and duration of the CPU spike.

Impact Card

The Impact card evaluates whether the CPU spike affects: Clients, Access Points, Gateways, and Switch operations.

History Card

The History card provides time-series visualizations that correlate CPU utilization with system resource metrics. The history view helps identify whether CPU spikes are related to: routing table growth, MAC table changes, ARP activity, packet exception handling, and unknown multicast traffic.

When the History card is expanded, HPE Aruba Networking Central displays detailed telemetry graphs for several switch metrics alongside CPU utilization.

Figure 2: History Card Expanded View

The expanded view includes the following metrics:

  • CPU Utilization graph displays the CPU usage trend over time and highlights periods where the utilization exceeded the configured threshold.

    This helps identify: sustained CPU spikes recurring utilization patterns correlation with other system metrics.

  • Unicast Route graph displays the unicast route table size over time. An increase in route entries may cause higher CPU utilization due to routing updates or control-plane processing.

  • MAC Address Count displays the number of MAC entries learned by the switch. A rapidly increasing MAC table can indicate: broadcast storms loops abnormal network behavior which may increase CPU usage.

  • ARP Utilization graph displays ARP table activity and utilization levels. High ARP activity may occur due to: large network segments ARP storms excessive host discovery activity.

  • IP Exceptions Statistics graph displays packets handled by the control plane instead of hardware forwarding. High IP exception packet rates may indicate: abnormal traffic patterns routing or ACL processing network misconfiguration These packets require CPU processing and may contribute to high CPU utilization.

  • Unknown Multicast Statistics graph displays unknown multicast packet statistics. Unexpected multicast traffic may lead to additional control-plane processing and increased CPU load.

Root Cause Analysis

HPE Aruba Networking Central analyzes system telemetry and identifies possible causes of high CPU utilization. Possible root causes include:

  • Configuration Issues—Configured CPU alert threshold is too low.

  • Firmware Issues—Switch firmware may have known high CPU utilization issues on specific platforms.

  • Network Instability—Port flaps detected, network loop detected, and high spanning-tree topology change notifications (TCNs).

  • Routing Instability—BGP peer flaps and OSPF peer flaps.

  • Resource Utilization—Large MAC address table, high ARP table count, large route table count, high VPort count.

  • Monitoring or Management Activity—Excessive SNMP read operations.

  • System Processes—Certain processes may generate high CPU utilization:

    • hpe-routing

    • sha1sum

    • hpe-restd

    • switchd_agentd

    • ovsdb-server

Recommended Actions

When you receive a Interface CRC Error alert:

  • Threshold Configuration—Increase the CPU alert threshold to above 50% or use system-defined baseline thresholds if the threshold is too sensitive.

  • Firmware Upgrade—Upgrade the switch to the recommended firmware version, especially on platforms such as AOS-CX 6000, AOS-CX6100, and AOS-CX 4000 where certain versions may cause high CPU utilization.

  • Network Stability—Checks Investigate and resolve: port flaps, network loops, and spanning-tree instability.

  • Routing Stability—Verify routing protocol health and investigate frequent BGP or OSPF neighbor flaps.

  • Resource Utilization Review—Review system resource tables: MAC table, ARP table, route table, VPort usage.

  • Monitoring Optimization— Reduce excessive SNMP polling frequency if necessary.

  • Process Investigation—Analyze system processes consuming high CPU resources and verify protocol health.

  • If CPU utilization remains high after corrective actions, collect diagnostics and open a support case.

Troubleshooting Card

Provides quick diagnostics including: CPU utilization insights, high CPU consuming processes, protocol activity indicators.

Related Events

This alert may correlate with: routing updates, topology changes, broadcast or multicast storms, excessive monitoring traffic, and control-plane packet processing.

Additional Notes

CPU utilization alerts are generated per device. Alerts automatically clear when CPU usage returns to normal levels. Sustained high CPU usage may impact switch performance and control-plane stability.