Quantum is a "virtual network service" that aims to provide a powerful API to define the network connectivity between devices from other OpenStack services. The Quantum service has an API that presents a logical abstraction for describing network connectivity. The service relies on a Quantum plugin to manage virtual and/or physical switches within the cloud data center to make sure those devices forward packets according to the behavior defined in the logical API model. This notion of a plugin is similar to how Nova can use different types of hypervisors to implement the same virtual server API.
The Quantum API utilizes the following logical abstractions:
Network: An isolated L2 segment, analogous to a single physical L2 switching device with an arbitrary number of ports.
Port: Provide a connection point to a Quantum network. Ports can also be configured to apply various network security, QoS, monitoring, etc. policies. Such policies are currently exposed by API extensions.
Attachment: Identifier of an interface device to be ''plugged in'' to a Quantum port, such as a vNIC from Nova.
For a detailed description of the Quantum API abstractions and their attributes, please see the Quantum API Guide.
