| In recent years, with the development of the network, the access of various new devices, the emergence of new services, the users want higher network bandwidth and lower network delay. But the current network architecture is not efficient and flexible enough to support these services.In order to solve these problems, the industry has already proposed a variety of new technologies to improve the performance of future network.As one of those new technologies, software-defined network technology(SDN) has been widely recognized. This paper conducts the research about applying the software-defined network technology on the access network.A new architecture of the traditional passive optical network (PON) system is proposed, combining the OpenFlow table with the passive optical network to improve the performance of the data forwarding efficiency.With the OpenFlow table, the passive optical network can forward data more flexibly and distinguish different businesses. So that the user data can be forwarded through passive optical network directly, and does not need to be sent to the broadband remote access server (BRAS), which reduces the pressure of broadband remote access server, improves the utilization rate of upstream bandwidth, and eases traffic. What's more, it can make a virtual isolation between different service traffic, which ensure the data transmission security.The work of this paper is as follows:1) The design of flexibly data forwarding PON systemThe Optical Network Terminal (OLT) of traditional PON system includes an Ethernet switch chip, but it does not support SDN protocol and only supports data forwarding based on media access control (MAC)address or IP address data. The data stream analysis of Ethernet switch chip is not detailed enough, which cannot distinguish the business types accurately. The OpenFlow table separates control and forwarding,supporting OpenFlow 12-tuple field matching. What's more, using mask can achieve fuzzy matching which can improve the flexibility of data forwarding. So in order to improve the performance of PON system data forwarding, a new architecture is proposed which applies the OpenFlow flow table into the traditional PON system.2) OVS hardware offloadingOVS is a high-quality, multi-layer virtual switch designed to realize automatism data forwarding and control for large-scale network. It can be programmed to expand and supports distributed environment with multiple physical machines. The application scenario of OVS is very rich. OVS has been designed on software, but the rate of software OVS exists a bottleneck,which cannot meet the rate requirements. In this paper, we implement the flow table function of software OVS on a hardware platform. Combined the software and hardware, the speed of data forwarding can be improved.What's more, we demonstrate its rationality with an experimental platform.3) Virtual domain partitioning and dynamic isolationWith the OpenFlow table, the PON system has the virtualization capabilities. It can build a new virtual domain based on the commands download by the software controller. Each virtual domain contains an independent flow table and several ports. What's more, the data forwarding efficiency between different ports in the same virtual domain is higher.Therefore, with the changing needs of the services, the system needs to re-divide the virtual domains according to the priorities of the business and the traffic to make full use of the system resources and improve system performance. In this paper, a dynamic partitioning algorithm for virtual domains is proposed based on how to determine whether virtual domains need to be dynamically allocated. Simulation tests are carried out to verify the correctness of the algorithm. |
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