engleski

Analysis of functional properties of controller in software defined networks

The software defined networks or software driven networks are new concept in modern telecommunication networks. In comparison with traditional networks, SDN (Software Defined Netowrk) introduces lower latency, fewer congestions and higher bandwith and throughput. The main feature of SDN architecture is separation control plane from data plane. Control plane consist of SDN controllers, which contain all of the intelligence of the network, while the data plane consists of network devices such as switches and routers. Controller in SDN contains two main APIs (Application Programming Interfaces): Northbound API and Southbound API. Bothbound API is responsible for communicating with various application written for SDN controllers, while the southbound API is indebted for communication with network devices, mostly Open vSwitches using REST (Representational State Transfer) API commands. When data plane doesn’t know what to do with appropriate packet, the same packet is being sent to the controller, which then decides what to do with the following packet. Communication between data plane and control plane is provided using protocol OpenFlow, the first and only standardized protocol by ONF (Open Network Foundation) for communication between network devices and SDN controllers. This communication channel is the most important in the SDN network and that’s why it’s secured using TLS or SSL sessions. Virtualization layer is a layer between control plane and data plane, and its main role is to abstract unnecessary traffic. FlowVisor is a device which is assigned to every controller, by certain defined rules, as a part of the network for which that controller is responsible. This paper describes the characteristics of the SDN in global and analyses functional characteristics SDN controller. Test cases were performed in a way to determine how much time it is need to SDN controller to send various number of REST commands to the Open vSwitch. The task was also to develop an aplplication for testing purposes. Furthermore, all network components (Open vSwitch, SDN controller OpenDayLight), used for this thesis, are located at the Combis d.d. facility in Zagreb. The results of testing show that time necessary for adding flows to the flow table increases exponentially with increasing the number of added flows. Also, multiple requests are handled by principle FIFO (First-In-First-Out) with appropriate buffer.

SDN ; control plane ; data plane ; OpenFlow ; FlowVisor

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