The Design And Implementation Of Openflow Controller Supporting Application Layer Policy Distribution

With the rapid development of networking technology, the size of the Internet has been greatly enlarged. The users quantity has also been expanded. And more and more applications have been deployed in the Internet. However, the networking technology cannot meet the rising need of network consumption. The problems of shortage of IP address and network security make the traditional network architecture is not able to meet the high requirements of applications. Under this circumstance, the concept of Software-Defined Networking was introduced to the public.The main idea of Software-Defined Networking is to decouple the control plane and the data forwarding plane. In this way, the lower layer network devices will be only in charge of data forwarding, and move the logical control of the network to the common computing environment, therefore, the intelligence of the network can be greatly enlarged. The Software-Defined Networking specifies the standard interface between the control plane and the data forwarding plane, which make the whole network architecture fully open. Gradually the Software-Defined Networking comes to widely attention from the industry.Although there have been many researches on the Software-Defined Networking technology, we still haven’t seen massive deployment in production environment. The major reason is that we still haven’t seen any mature way to transfer the traditional network to the OpenFlow network. Current controller in the Software-Defined Networking is only able to manage the pure Software-Defined Networking, and it is not able to support traditional network. It is because the logical intelligence of the controller depends on the network topology, and this topology will be broken when the network contains traditional devices. Moreover, when more than one applications working in the network, policy conflict will happen when different applications send different forwarding policy, which will affect the network functions.To solve this problem, this thesis proposed three solutions, which enables the cooperation between traditional network and the OpenFlow network. Three novel ideas are proposed as follows.Firstly, this thesis proposed to change the managed object of the controller from the whole network to a single device. In this way the controller can work without build up a topology of the network.Secondly, this thesis proposed an application layer policy mechanism in the OpenFlow controller, so that messages from different OpenFlow switches can be handled by different applications set. In this way the OpenFlow switches can meet different requirements.Thirdly, this thesis proposed a flow-mod rules pool and conflict resolution mechanism. The application cannot send messages to the switch directly. Instead, the rules must be stored in the flow-mod rules pool for each switch, and then the conflict resolution module pick the best rule from the rules pool and send the message to the switch via the controller.This thesis also implements a prototype controller, which tests and verifies the practicability of the solutions the thesis proposed.