Enhancing traditional networking solutions to provide rich cloud networking is challenging. Traditional networking is not designed to scale to cloud proportions or to configure automatically.
The original Nova network implementation assumed a very basic model of performing all isolation through Linux VLANs and IP tables. Quantum introduces the concept of a plugin, which is a pluggable back-end implementation of the Quantum API. A plugin can use a variety of technologies to implement the logical API requests. Some Quantum plugins might use basic Linux VLANs and IP tables, while others might use more advanced technologies, such as L2-in-L3 tunneling or OpenFlow, to provide similar benefits.
The current set of plugins include:
Open vSwitch. http://www.openvswitch.org/openstack/documentation
Cisco. quantum/plugins/cisco/README and http://wiki.openstack.org/cisco-quantum
Linux Bridge. quantum/plugins/linuxbridge/README and http://wiki.openstack.org/Quantum-Linux-Bridge-Plugin
Nicira NVP. quantum/plugins/nicira/nicira_nvp_plugin/README and http://www.nicira.com/support.
Ryu. quantum/plugins/ryu/README and http://www.osrg.net/ryu/using_with_openstack.html
NEC OpenFlow. http://wiki.openstack.org/Quantum-NEC-OpenFlow-Plugin
Plugins enable the cloud administrator to weigh different options and decide which networking technology is right for the deployment.