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How to Setup CML in Proxmox Server

December 25, 2025 · 2 min read/Cisco CML/Proxmox VE/Nested Virtualization

Prerequisites

  • A working Proxmox VE server.
  • Cisco CML Personal license.
  • Downloaded CML files from Cisco:
    • CML Installer ISO (cml2.9.1-7.iso is the latest as of Dec 2025)
    • CML Reference Platform ISO (refplate_2.9.1.iso)

Step 1: Enable Nested Virtualization (Host Level)

CML requires nested virtualization to run router/switch nodes. Run this on your Proxmox host shell:

  1. Check if enabled: cat /sys/module/kvm_intel/parameters/nested (or kvm_amd for AMD). It should return Y or 1.

  2. If N or 0, enable it:

    • Intel: echo "options kvm-intel nested=Y" > /etc/modprobe.d/kvm-intel.conf
    • AMD: echo "options kvm-amd nested=1" > /etc/modprobe.d/kvm-amd.conf

  3. Reboot the Proxmox host or reload the KVM module.

Step 2: Upload CML ISOs

  1. In Proxmox, navigate to your storage drive (e.g., local).
  2. Select ISO Images > Upload.
  3. Upload both the CML Installer ISO and the Reference Platform ISO.

Step 3: Create the Virtual Machine

Create a new VM with the following specific settings:

  • General: Name the VM (e.g., CML-Personal).
  • OS: Select the CML Installer ISO. Guest OS: Linux (6.x - 2.6 Kernel).
  • System: Leave as default (OVMF, i440fx). I made mistake on image below had to change it afterward.
  • Disks: Minimum 32 GB (SCSI or VirtIO). Note: 150GB+ is recommended if you have CML personal License to store any images and labs. I am using 150GB
  • CPU: Minimum 4 Cores. CRITICAL: Set the Type to Host (enables nested virtualization for the VM).
  • Memory: Minimum 8192 MB (16384 MB+ highly recommended). I am using around 32 GB
  • Network: VirtIO (Paravirtualized), bridged to your active network (e.g., vmbr0). Leaving it default

Step 4: Mount the Reference Platform ISO

Before booting the VM:

  1. Go to the VM's Hardware tab in Proxmox.
  2. Click Add > CD/DVD Drive.
  3. Select the CML Reference Platform ISO (attach it to an available IDE or SCSI slot).
  4. Make sure to add a EFI disk 5. Make sure to check the boot order and everything checked

    [!Tips] Keep eye of task Log list, if you made any mistake it will show it there

Step 5: Install CML

  1. Start the VM and open the Console.
  2. Follow the text-based setup prompts (set timezone, admin username/password, and networking).
  3. When asked about the Reference Platform, select Copy to Disk (this copies the images from the second ISO to your VM's hard drive).
  4. Once the installation finishes, the VM will provide an IP address on the console screen.

Step 6: Licensing and Access

  1. Navigate to https://<CML-VM-IP> in your web browser.
  2. Log in using the admin credentials you created.
  3. Go to Tools > Licensing and register the instance using your CML Personal token. ( They have moved the License to Cisco U site now)