Secure Transmission Subsystem Based On SDN

The existing network exists some problems like inflexible transmission path, vulnerable to be caught data packet then leak the plaintext and so on. This paper solves the problems based on software defined network architecture. Software defined network is a newly-developing technology, whose core idea includes the Separation of control plane and data plane of the network, the implementation of the programmable interfaces by switch and the centralization of the network controlling by controller. The core of SDN is Controller, which manages all the network devices in data plane, and offers resource scheduling interface for the upper-layer applications. It uses OpenFlow protocol to communicate between controller and switch.This paper is based on the SDN architecture, and the subsystem uses the SDN controller to transmit data by means of Time Slot Forwarding Strategy. The specific operation is to distribute the OpenFlow flow table of the new path to the switch, and remove the old path flow table item periodically. The Time Slot Forwarding refers to the different transmission paths during the data transmission process to prevent the transmission path from being solidified and ensure the security of data transmission. The multi-connection Strategy, splits the data into different parts, and uses different connections to send different data, to protect the data from being intercepted in the transmission process. Through the time slot forwarding and multi-connection strategy, the data transmission is more secure than the traditional network.According to the architecture of software defined network, this paper designs and implements the system according to the requirements of time slot forwarding and multi-connection strategy. It adds time-slot forwarding module to the ONOS controller and provides a REST interface for other applications. On the user side, a client is designed to split and restore the data and achieve multi-connection strategy.In this thesis, firstly, it introduces the related technologies of data transmission, including SDN and traditional network. Secondly, it designs the whole system, including the overall architecture, and the typical process of system. Then it compares the ratio of packet loss by different implementations of time slot forwarding and solve the packet loss problem by using time series forecasting which is based on maximum likelihood estimation to predict the delay. In the end, it builds an experimental network to test the system, which verifies the feasibility of the system designed in this paper.