We have the following section at OSP17.1 networking guide, https://docs.redhat.com/en/documentation/red_hat_openstack_platform/17.1/html-single/configuring_red_hat_openstack_platform_networking/index#enabling-compute-metadata-access_connect-instance.

The guide explains how to enable metadata service for external provider service. But it describes about dhcp agent.
ML2/OVN deployment doesn't use dhcp agent and this is limited to ML2/OVS.
So, we need to have a sentence which describes this is only applicable to ML2/OVS or move this section to ML2/OVS related sections.