Copy pasting the yaml describe in this documentation, will lead to a degraded machineconfigpool.

~~~
Configuring MetalLB with secondary networks
Enable forwarding for a specific secondary interface, such as bridge-net by creating and applying a MachineConfig CR.
Save the following YAML in the enable-ip-forward.yaml file:

apiVersion: machineconfiguration.openshift.io/v1
kind: MachineConfig
metadata:
  labels:
    machineconfiguration.openshift.io/role: <node_role> 
  name: 81-enable-global-forwarding
spec:
  config:
    ignition:
      version: 3.2.0
    storage:
      files:
      - contents:
          source: data:text/plain;charset=utf-8;base64,`echo -e "net.ipv4.conf.bridge-net.forwarding = 1\nnet.ipv6.conf.bridge-net.forwarding = 1\nnet.ipv4.conf.bridge-net.rp_filter = 0\nnet.ipv6.conf.bridge-net.rp_filter = 0" | base64 -w0`
           verification: {}
        filesystem: root
        mode: 644
        path: /etc/sysctl.d/enable-global-forwarding.conf
  osImageURL: ""
~~~

The following part of the machineconfig need to be interpreted by a shell before applying the result.

`echo -e "net.ipv4.conf.bridge-net.forwarding = 1\nnet.ipv6.conf.bridge-net.forwarding = 1\nnet.ipv4.conf.bridge-net.rp_filter = 0\nnet.ipv6.conf.bridge-net.rp_filter = 0" | base64 -w0`

If not, you will fall into an error in the mcp.
# oc get mcp master  -o yaml
...
  - lastTransitionTime: "2024-11-29T14:19:58Z"
    message: |
      Failed to render configuration for pool master: could not generate rendered MachineConfig: parsing Ignition config spec v3 failed with error: config is not valid
      Report: error at $.storage.files.0.contents.source, line 1 col 75: invalid data character
      warning at $.storage.files.0.filesystem, line 1 col 306: Unused key filesystem

4.16, but will be the same on 4.17    

    oc apply -f mc-global-forward

    1.
    2.
    3.
    

    machineconfigpool is in degraded

    machineconfig created and machineconfigpool applied