python-neutronclient/doc/source/cli/osc/v2/subnet-onboard.rst

network onboard subnets

network onboard subnets enables a subnet to be adopted or "onboarded" into an existing subnet pool. The CIDR of the subnet is checked for uniqueness across any applicable address scopes and all subnets allocated from the target subnet pool. Once onboarded, the subnet CIDR is added to the prefix list of the subnet pool and the subnet appears as though it has been allocated from the subnet pool. The subnet also begins participating in the applicable address scope if the subnet pool belongs to one.

Network v2

openstack.neutronclient.v2