## 4 Solution of Requirements and Inspection Methods
### Open-Flow Proxy Construction
Leveraging the SD-WAN switch, it achieves Packet-In event reporting and accommodates data flow table configurations, enabling a seamless integration of the GPON network system into SD-WAN controller management and assimilating the GPON network system into the realm of software-defined networking. 1. The OpenFlow Proxy module  
This module operates as a socket daemon on the Linux operating system of the GPON OLT system. Its role is to facilitate the transmission of control commands between the SD-WAN controller and the OpenFlow switch. The primary functionalities include the following:  
* Receiving and transmitting control messages between the OpenFlow switch and SD-WAN controller and modifying field data to ensure the accurate transmission of virtual ports messages to both the SD-WAN controller and the OpenFlow switch. Figure 22: Architecture of the open-flow exchange function. * Utilizing the OLT management API to convert the PON-Port status into a virtual port status and transmitting it to the SD-WAN controller. * Handling statistics request control commands initiated by the controller. This acquires packet delivery data for virtual ports through the OLT management system, transmitting it back to the controller for calculations in management algorithms such as load balancing and QoS. The design of the OpenFlow Proxy software module is primarily divided into three components, as shown in Figure 23. The control channel module, encompassing command parser and dispatcher functionalities, adheres to the specifications outlined in the OpenFlow specification. It processes the exchange of control messages as per OpenFlow ports, the OpenFlow control channel, and the OpenFlow switch protocol. Additionally, it rewrites pertinent message field data to achieve the virtualization of ONU ports. This module functions as an intermediary for communication within the database system. When the control channel module receives or necessitates the dispatch of control messages, this module adeptly translates and modifies port number field data, ensuring the precise alignment of ONU Ports with VLAN tags [41] to attain the desired effect of virtual ports. Conversely, the traffic management module establishes communication with the ONU management API. Through instantaneous inter-module communication, it conveys the real-time connection statuses of virtual ports and facilitates pertinent management configurations within the GPON network. The control channel module's paramount function lies in the maintenance and transmission of OpenFlow control messages. It deciphers packet control message types, invoking the corresponding management API for processing. Illustrated in Figure 24 the control channel operates with a status diagram delineating the connection between the switch and controller. Upon the initiation of the proxy, the connection status is denoted as Not Ready. At this juncture, the operating system kernel opens ports in readiness to receive connection initiation from the OpenFlow switch. Upon the receipt of the connection packet from the switch, the proxy, in turn, rewrites the destination field of the control message, forwarding it to the SD-WAN controller. Figure 23: Flowchart of the GPON OLT OpenFlow proxy. Upon the completion of the exchange of OpenFlow messages, the module transitions into a state of proxy readiness. It initiates the discernment of control messages received through the port, parsing their types, effectuating processing, modifying field data, and subsequently dispatching the data message, thereby concluding a processing cycle. 2. Virtual port module It is an aim of the GPON SD-WAN virtual switch to encapsulate each ONU as a port within a conventional switch, enabling the SD-WAN controller to perceive the GPON system as a singular OpenFlow switch under its aegis, without encroaching upon the functionality of the GPON. This module, in consonance with diverse control messages, adjusts the transmitted control message fields.