Managing MAC address pools for network interfaces

KubeMacPool allocates MAC addresses for virtual machine (VM) network interfaces from a shared MAC address pool. This ensures that each network interface is assigned a unique MAC address.

A virtual machine instance created from that VM retains the assigned MAC address across reboots.

Note

KubeMacPool does not handle virtual machine instances created independently from a virtual machine.

Managing KubeMacPool by using the CLI

You can disable and re-enable KubeMacPool by using the command line.

KubeMacPool is enabled by default.

Prerequisites

You have installed the OpenShift CLI (oc).

Procedure

To disable KubeMacPool in two namespaces, run the following command:

$ oc label namespace <namespace1> <namespace2> mutatevirtualmachines.kubemacpool.io=ignore

To re-enable KubeMacPool in two namespaces, run the following command:

$ oc label namespace <namespace1> <namespace2> mutatevirtualmachines.kubemacpool.io-

Customizing the MAC pool range

KubeMacPool works by allocating MAC addresses to VMs from a range. The rangeStart and rangeEnd parameters in the HyperConverged custom resource (CR) define the MAC pool range.

As a cluster administrator, you can configure this range to ensure that MAC addresses for VMs hosted on OpenShift Virtualization do not conflict with other virtualization solutions on the same network.

Prerequisites

You have cluster administrator access on an OpenShift Container Platform cluster.
You have installed the OpenShift CLI (oc).

Procedure

Edit the HyperConverged CR by running the following command:

$ oc edit hyperconverged kubevirt-hyperconverged -n openshift-cnv

Update the HyperConverged CR to configure the rangeStart and rangeEnd parameters that define your required MAC address range:

apiVersion: hco.kubevirt.io/v1beta1
kind: HyperConverged
metadata:
  name: kubevirt-hyperconverged
spec:
  kubeMacPoolConfiguration:
    rangeStart: "AA:00:00:00:00:00"
    rangeEnd: "FD:FF:FF:FF:FF:FF"
# ...

Verification

Run the following command and observe the output:
```
$ oc get hco kubevirt-hyperconverged -n openshift-cnv -o=jsonpath='{.spec.kubeMacPoolConfiguration}'
```
If you have successfully applied the configuration changes, the output shows the new MAC pool range you have configured:

Example output:
```
{
  "rangeStart": "AA:00:00:00:00:00",
  "rangeEnd": "FD:FF:FF:FF:FF:FF"
}
```
Optional. Create a new VM and run the following command to check the MAC address of the VM’s network interface:
```
$ oc get vmi <vm-name> -o=jsonpath='{.status.interfaces[0].macAddress}'
```
Example output:
```
macAddress: AA:00:00:00:00:04
```
If you have successfully applied the configuration changes, the macAddress field in the VM interface is within the range you specified in your kubeMacPoolConfiguration, between the value of rangeStart and rangeEnd.