A single PVI VNIC is one VNIC configured in a PVI. The single PVI VNIC offers one server connection into the Oracle SDN environment. Even though this is a valid configuration, a typical deployment has two PVI VNICs (HA) for redundancy.
add vnic VNIC-name.server-profile-name public-network-name
Each new server is added to the public cloud through the VNICs that connect the server to the public cloud.