The story of an API
By analogy, the OpenStack compute service provides an API that provides a virtual server abstraction to imitate the compute resources. The network service and compute service perform in the same way, where we come to a new generation of virtualization in network resources such as network, subnet, and ports, and can be continued in the following schema:
Network: As an abstraction for the layer 2 network segmentation that is similar to the VLANs
Subnet: This is the associated abstraction layer for a block of IPv4/IPv6 addressing per network
Port: This is the associated abstraction layer that is used to attach a virtual NIC of an instance to a network
Router: This is an abstraction for layer 3 that is used to perform routing between the networks
Floating IP: This is used to perform static public IP mapping from external to internal networks
