As features that extend Neutron's functionality are added to it, most are implemented as extensions to the core API. For more information on how to utilize some of the included extensions, refer to the Neutron API documentation found at http://developer.openstack.org/api-ref-networking-v2-ext.html.
Many third-party extensions require the use of additional software or hardware that are often proprietary and may have associated support and operational costs. A production-grade OpenStack cloud does not require the use of third-party extensions and can simply leverage the open-source compute and networking technologies outlined in this book. Proprietary software and hardware may provide additional features, functionality, and stability that are not yet available with open-source alternatives and should be taken into consideration when developing your OpenStack network architecture.
In Appendix B, Virtualizing the Environment, we will take a look at the use of the virtualization software known as VirtualBox as an alternative to physical hardware when completing the exercises outlined in this book.