Describe the issue:

OVN-kubernetes is the default cluster network provider in OCP for some time now. It requires a specific setup for ODF when it is deployed in external mode. This is a common issue that should be documented in ODF docs.

Documentation should state a note or something which advises user to consider turning on routing via host if the external cluster is accessible via a private network. This is quite a common configuration especially on baremetal OCP installations. Users should execute following command:

{code}
oc patch network.operator cluster -p '{"spec":{"defaultNetwork":{"ovnKubernetesConfig":{"gatewayConfig":{"routingViaHost": true}}}}}' --type=merge
{code}

This is especially confusing since `rook-ceph-tools` pod is using different network settings, see related BZ.


Describe the task you were trying to accomplish:

Install ODF in external mode connecting it to a Ceph cluster accessible via private network configured by NMState operator.

Suggestions for improvement:

Users should execute following command:

{code}
oc patch network.operator cluster -p '{"spec":{"defaultNetwork":{"ovnKubernetesConfig":{"gatewayConfig":{"routingViaHost": true}}}}}' --type=merge
{code}

Document URL:
https://access.redhat.com/documentation/en-us/red_hat_openshift_data_foundation/4.10/html/deploying_openshift_data_foundation_in_external_mode/deploy-openshift-data-foundation-using-red-hat-ceph-storage#doc-wrapper

Chapter/Section Number and Title:
Deploying OpenShift Data Foundation in external mode > Chapter 2. Deploy OpenShift Data Foundation using Red Hat Ceph storage

Product Version: 4.10 (should apply to previous versions as well)

Environment Details: Baremetal (may be importatn 

Any other versions of this document that also needs this update:

Additional information:
https://chat.google.com/room/AAAABTq-uCM/ibDdFdKeuP4
https://chat.google.com/room/AAAABTq-uCM/xE4cR1lCRDk