Cisco Identity Services Engine Installation Guide, Release 3.5

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Virtual machine size recommendations

Updated: May 28, 2026

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Overview

Provides minimum resource specifications and configuration guidelines for Cisco ISE virtual appliances, ensuring optimal performance and reliability. Outlines best practices for VM sizing, deployment, and allocation of CPU, memory, disk, and network resources to match production standards and support high session capacity.

The VM appliance specifications should match those of physical appliances used in a production environment.

Follow these guidelines when allocating resources for the appliance:

  • Do not share or oversubscribe resources across multiple guest VMs. Use OVF templates to assign adequate resources. If you install Cisco ISE manually using the ISO image, ensure you assign equivalent reservations.

    If you do not allocate the specified resources, performance degradation or service failure might occur. To avoid these issues, deploy dedicated VM resources.

    If you deploy Cisco ISE manually without the recommended reservations, you must closely monitor your appliance’s resource utilization. Increase resources as needed to ensure proper health and functioning of the Cisco ISE deployment.

  • If you are using the OVA templates for installation, check these settings in the Edit Settings page (under the Virtual Hardware tab), after the installation is complete:

    • Ensure that you assign the resource reservations that are specified in the VMware virtual machine requirements section in the CPU/Memory Reservation field to ensure proper health and functioning of the Cisco ISE deployment.

    • Ensure that the CPU usage in the CPU Limit field is set to Unlimited. Setting a limit for CPU usage impacts system performance. If a limit is set, shut down the VM client, remove the limit, and restart the client.

    • Ensure that the memory usage in the Memory Limit field is set to Unlimited. Setting a limit for memory usage will impact the system performance.

    • Ensure that the Shares option is set as High in the Hard Disk area.

      Admin and MnT nodes rely heavily on disk usage. Using shared disk storage VMware environment might degrade disk performance. You must increase the number of disk shares allocated to a node to improve performance.

  • You can deploy Policy Service nodes on VMs with less disk space than Administration or Monitoring nodes. The minimum disk space for any production Cisco ISE node is 300 GB.

  • VMs can be configured with one to six NICs. Configure VMs with at least two NICs when possible. Additional interfaces support services such as profiling, guest services, or RADIUS.

Note

If you decrease the RAM or CPU allocation for a VM, you must reimage Cisco ISE with the new VM configuration. However, increasing the RAM or CPU capacity does not require reimaging.