# Software Defined Networking Architecture for Energy Transaction in Smart Microgrid Systems
## 2 Related Work  
Ensuring suitable quality of service (QoS) for service-oriented applications (SOAs) is another challenge in traditional architectures, according to [PERSON] et al. [13]. Transactive energy can be classified as an SOA because it is a real-time application sensitive to packet loss. Their study confirmed the challenges that traditional IP infrastructure presented for SOAs. They focused on an SOA-based software-defined network (SDN) solution that guarantees the required end-to-end QoS by improving the control algorithm that mitigates packet loss. Standardized routing protocols are introduced in traditional IP networks to mitigate the static configuration challenges in the traditional IP architecture. However, [PERSON] et al. [14] perform a failover performance analysis between three routing protocols, RIPv2, OSPF, and EIGRP (enhanced interior gateway routing protocol). Their simulations show that the failover switching delay is significant. The delay is due to the time it takes to repopulate routing tables. For real-time applications, the delay will cause errors in the exchange of information. Another challenge of traditional IP Networks is proprietary hardware and features. [PERSON] et al. [15] state that existing traditional IP networks consist of multivendor legacy equipment with proprietary protocols, features, and capabilities. They have also been installed, configured, and operated statically through vendor-specific management systems. This configuration expects to adapt slowly to the new challenges required from applications such as transactive energy. Therefore, transactive energy requires a new network architecture that supports real-time adaptation and flexibility. The increasingly complex network requirements resulted in the emerging software-defined network (SDN) to allow network administrators to manage a network through an abstract of the lower-level functionality. SDN separates the data plane and the control plane in a network. It removes the control function from the network devices and allows network operators to manage and optimize network resources from a controller. SDN thereby simplifies the remote device to a network switch. [PERSON] et al. [16] confirm this by stating that SDN architecture emerged to satisfy complex networking requirements due to the limitation of traditional networking architecture. A traditional architecture faces a complex problem when adding or removing a device from a network, confirming a flexibility limitation. Furthermore, the configuration of the devices in traditional network architecture is complex and, most of the time, proprietary to the device's manufacturer. A typical example is the enhanced interior gateway routing protocol (EIGRP) developed by Cisco Systems, and only Cisco networking devices support this protocol. This unique function often requires a skilled and qualified individual to troubleshoot, configure or install a new device in the network. This problem suggests that the traditional network architecture faces challenges of network inflexibility and hence the need to develop a dynamic architecture. It is important to note that an SDN architecture described by [PERSON] et al. [16] can meet this requirement. An SDN architecture simplifies the programmability of the network, enabling network operators to manage and configure network elements more easily. However, the authors further state that SDN has scalability limitations due to the centralized control nature of software-defined networks. [PERSON] et al. [17] identify three planes in an SDN architecture: data plane, control plane and application/management plane. Figure 3 illustrates the layer view of the SDN architecture, indicating the applications in the management plane. The SDN architecture in abovementioned Figure 3 was adapted from [PERSON] et al. [17] and it uses the southbound interface (SBI) for protocols such as OpenFlow, Netconf, and SNMP to separate the control plane and data plane.