Following the rather stark change of direction after the last milestone (see my last post), I have worked on the integration of my project with Johannes Wegener’s: OpenWifi.
For my software-defined networking (SDN) agent, I have added support for configuration through a UCI config file as well as process management through procd. This ties the daemon in neatly with the LEDE/OpenWRT system. Now, parameters such as the SDN controller’s address are read from this file and the configuration can be reloaded at runtime without stopping the agent.
Using the UCI system also exposes the configuration parameters to Johannes’ OpenWifi system. He and I discussed the bootstrapping process with our mentor and we have come up with the following idea: When a newly installed LEDE/OpenWRT access point first boots, it discovers the OpenWifi server via mDNS and fetches its configuration from it. With the address contained in the configuration, my SDN agent on the access point is able to connect to the SDN controller and thus integrate automatically with an existing centrally managed deployment. In the event of a configuration parameter change (e.g. a switch to a different SDN controller), OpenWifi can trigger a configuration reload to quickly update all access points in the network.
On the controller side, I have implemented a REST client to interface with OpenWifi. Through it, the controller can register with the OpenWifi server. During the registration, it installs its address and OpenFlow listening port in the UCI configuration which later gets sent to access points.
I have also begun writing a REST interface for my controller to offer more comfortable management of SDN applications and the network state. Right now, I can query the controller about its resources: access points, switches and clients. With the basics in place, expanding the interface to expose more SDN functionality should be pretty straightforward.
During the final part of this year’s GSoC, I want to focus on adding functionality, testing and documentation. I will spend the remaining weeks of the project like this:
1) write an SDN application
2) expose the app’s functionality via the controller’s command-line and REST interfaces
3) test it on the university department’s testbed
4) document its usage
5) goto 1)
Since the foundation for the SDN applications is in place and running, I am optimistic about getting a lot done during August. I will start with a client hearing map that keeps track of associated and unassociated clients in the vicinity of the deployment’s access points. Leveraging the hearing map, I want to implement a client load balancer that distributes associated clients evenly across available access points. I will also look into automated channel selection to avoid interference between neighbouring access points.
Finally, I would like to wrap up the controller in a docker image for easy deployment.