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Managing the link state of a virtual machine interface

You can manage the link state of a primary or secondary virtual machine (VM) interface by using the OKD web console or the CLI. By specifying the link state, you can logically connect or disconnect the virtual network interface controller (vNIC) from a network.

OKD Virtualization does not support link state management for Single Root I/O Virtualization (SR-IOV) secondary network interfaces and their link states are not reported.

You can specify the desired link state when you first create a VM, by editing the configuration of an existing VM that is stopped or running, or when you hot plug a new network interface to a running VM. If you edit a running VM, you do not need to restart or migrate the VM for the changes to be applied. The current link state of a VM interface is reported in the status.interfaces.linkState field of the VirtualMachineInstance manifest.

You can set the link state of a primary or secondary virtual machine (VM) network interface by using the web console.

Prerequisites

  • You are logged into the OKD web console.

Procedure

  1. Navigate to Virtualization → VirtualMachines.

  2. Select a VM to view the VirtualMachine details page.

  3. On the Configuration tab, click Network. A list of network interfaces is displayed.

  4. Click the Options menu kebab of the interface that you want to edit.

  5. Choose the appropriate option to set the interface link state:

    • If the current interface link state is up, select Set link down.

    • If the current interface link state is down, select Set link up.

You can set the link state of a primary or secondary virtual machine (VM) network interface by using the CLI.

Prerequisites

  • You have installed the OpenShift CLI (oc).

Procedure

  1. Edit the VM configuration to set the interface link state, as in the following example:

    apiVersion: kubevirt.io/v1
kind: VirtualMachine
metadata:
  name: my-vm
spec:
  template:
    spec:
      domain:
        devices:
          interfaces:
            - name: default (1)
              state: down (2)
              masquerade: { }
      networks:
        - name: default
          pod: { }
# ...
    1 The name of the interface.
    2 The state of the interface. The possible values are:

    • up: Represents an active network connection. This is the default if no value is specified.

    • down: Represents a network interface link that is switched off.

    • absent: Represents a network interface that is hot unplugged.

      If you have defined readiness or liveness probes to run VM health checks, setting the primary interface’s link state to down causes the probes to fail. If a liveness probe fails, the VM is deleted and a new VM is created to restore responsiveness.

  2. Apply the VirtualMachine manifest:

    $ oc apply -f <filename>.yaml
Verification

  • Verify that the desired link state is set by checking the status.interfaces.linkState field of the VirtualMachineInstance manifest.

    $ oc get vmi <vmi-name>
    Example output
    apiVersion: kubevirt.io/v1
kind: VirtualMachineInstance
metadata:
  name: my-vm
spec:
  domain:
    devices:
      interfaces:
      - name: default
        state: down
        masquerade: { }
  networks:
  - name: default
    pod: { }
status:
  interfaces:
    - name: default
      linkState: down
# ...