Читать книгу The Smart Cyber Ecosystem for Sustainable Development - Группа авторов - Страница 50

The open source OpenFlow protocol enables the realization of the SDN technology. It has been used for researching different protocol designs over existing hardware. OpenFlow is widely used for the communication between the control and the data planes. It is developed by the Open Networking Foundation (ONF). It is the interface between devices and the SDN controller, providing the rules for switching control features from network devices to the central controllable software. It has a controller and a switch, functioning as secure channel as shown in Figure 2.7. The controller can modify, discard, and send packets to the switch. The path of the packet is determined at the times of packet transmission. OpenFlow calculates the path and sends it to the switch, which stores it in the Flow Table. When a switch receives a packet, it looks up the flow table and sends it along the stored path [11]. The primary task of the switch is to exchange data using flow tables, which are controlled by the controller of the CP. This architecture simplifies the design of switches and reduces their tasks, because they have become just data deliverers, without being required to perform any of the control functions.

Figure 2.7 The OpenFlow architecture.

The implementation of an SDN controller can be centralized or distributed. In the centralized implementation, a single SDN controller centrally controls and manages all network devices, which would possibly lead to bottleneck. Distributed implementation of the SDN controller would overcome this issue. The CP may include multiple controllers, depending on the network size. This will help boosting the network performance.