OpenFlow

The OpenFlow testbed

OpenFlow is an emerging new technology, the most widely used Software Defined Networking (SDN) enabler. OpenFlow's Whitepaper is giving more information about the protocol, the system architecture and the uses cases. NITOS Testbed currently features two OpenFlow ethernet switches - Pronto 3290. The two switches are interconnected through a single link, whereas each of the testbed physical machines (a.k.a. nodes) is connected to one of the two switches. A suitable convention has been adopted, connecting the nodes with odd and even identifier to the first and second switch respectively.

The testbed provides remote OpenFlow access, enabling the user to create an OpenFlow slice, related to an experiment slice that already has available. The OpenFlow slice is implemented by the Stanford's software tool, named FlowVisor, that creates slices on the OpenFlow switches, enabling the parallel access to them by separate users. In a transparent way from the user perspective, the switches ports, which are used by the user reserved nodes, are assigned to the user OpenFlow slice. The whole process is orchestrated by the NITOS scheduler, configuring appropriately the FlowVisor each time that a new node reservation is behaved.

In summary, the remote user of the NITOS testbed is able to create a slice, reserve nodes for this slice (through the NITOS scheduler) and run an OpenFlow experiment with use of this slice. Then, the testbed provides transparently an abstract OpenFlow switch for this slice, that conceptually is equivalent to a physical OpenFlow switch that includes only the ports that the slice nodes are connected to. The OMF framework is the experiment orchestrator that raises the OpenFlow controller and initiates the experiment process.