Neutron and SDN
P.S: This picture gives an overall architecture about Neutron and SDN controller that are integrated together.
When an OpenStack user performs any networking related operation (create/update/delete/read on network, subnet and port resources) the typical flow would be as follows:
- The user operation on the OpenStack dashboard (Horizon) will be translated into a corresponding networking API and sent to the Neutron server.
- The Neutron server receives the request and passes the same to the configured plugin (assume ML2 is configured with an ODL mechanism driver and a VXLAN type driver).
- The Neutron server/plugin will make the appropriate change to the DB.
- The plugin will invoke the corresponding REST API to the SDN controller (assume an ODL).
- ODL, upon receiving this request, may perform necessary changes to the network elements using any of the southbound plugins/protocols, such as OpenFlow, OVSDB or OF-Config.
We should note there exists different integration options with the SDN controller and OpenStack; for example:
- one can completely eliminate RPC communications between the Neutron server and agents on the compute node, with the SDN controller being the sole entity managing the network
- or the SDN controller manages only the physical switches, and the virtual switches can be managed from the Neutron server directly.
P.S: This picture shows the process flow between agents, api server and ovs when creating a VM.
How OpenDaylight to integrate with Neutron
How is ONOS to integrate with Neutron
onos-networking plugin just forwards (or calls) REST calls from nova to ONOS, and OpenstackSwitching app receives the API calls and returns OK. Main functions to implement the virtual networks are handled in OpenstackSwitching application.
P.S: ONOS provides its ONOSMechanismDriver instead of OpenvswitchMechanismDriver
Here is an article to talk about writing a dummy mechanism driver to record variables and data in logs