1 Enhancing the Quality Level Support for Real-time Multimedia Applications in Software-Defined Networks Francesco Ongaro † , Eduardo Cerqueira ∗ , Luca Foschini † , Antonio Corradi † , and Mario Gerla ‡ † Department of Computer Science and Engineering, University of Bologna, Bologna, Italy francesco.ongaro@studio.unibo.it, {antonio.corradi, luca.foschini}@unibo.it ∗ Institute of Technology, Federal University of Par´ a, Bel´ em, Brazil cerqueira@ufpa.br ‡ Department of Computer Science, University of California Los Angeles, Los Angeles, USA gerla@cs.ucla.edu Abstract—Nowadays, the explosive growth of real-time appli- cations that need stringent Quality of Service (QoS) and Quality of Experience (QoE) support, forces network programmers to design network protocols that deliver specified performance guarantees. This paper exploits the use of Software-Defined Networking (SDN) in conjunction with the OpenFlow protocol to differentiate network services with quality level assurance and to respect agreed Service Level Agreements. Initially, we define a Management and Orchestration architecture that allows us to manage the network in a modular way. Then, we provide a seamless integration of the proposed architecture and the SDN standard following the separation between the control and data planes. Finally, we give an Integer Linear Programming formulation of the problem of enhancing QoS and QoE in SDNs in terms of packet loss and delay, taking into account the network constraints and the requirements of real-time applications, i.e., maximum acceptable packet loss and delay rates. Given the optimal solution of the problem, we evaluate the impact and benefits of the proposed scheme by means of the Mininet network emulator. Index Terms—Software-Defined Networking; OpenFlow; Wire- less and Wired Networks; Quality of Service; Quality of Expe- rience; Emulator; Multi-Commodity Flow; I. I NTRODUCTION In the last few years, there has been a continuous evolution of network services and applications. Unfortunately, the net- work infrastructure system has been maintained almost in the same shape for decades according to the phenomenon known as ”Internet ossification”. The Software-Defined Networking (SDN) [1] paradigm is one of the best and most attractive solution for enhancing the Internet with more flexibility and adaptability. SDN allows a logically centralized software program to control the behavior of an entire network by decoupling the routing decision tier from the forwarding layer. The OpenFlow protocol [2] makes the communication between the control plane and the data plane possible. Thus, it allows us to write high-level control programs that specify the behavior of the network components and that can take care of various networking tasks, including resource management procedures. One of the main important networking problem is the lack of efficient resource management schemes to provide Quality of Service (QoS) and Quality of Experience (QoE) support for real-time applications, especially in networks affected by packet loss and delay. For example, the Voice over IP (VoIP) and the Interactive-Video services are not tolerant to packet loss that should be no more than 1%, especially if the services use compressed codec. The latency is also very important and it should be no more than 150ms between two end-points, i.e., one-way latency [3]. The paper addresses the issues above proposing a solution that shows several novel aspects. Firstly, we define a modular and extensible QoS architecture providing a seamless integra- tion between our solution and the standard SDN paradigm. Secondly, by exploiting OpenFlow in SDNs, we show how our proposal can be used for managing differentiated network services for multimedia applications with quality level support in wired and wireless environments. Since we are also interested in dealing with multi- commodity flows, we present in Section III an Integer Lin- ear Programming (ILP) formulation that considers the well- known Multi-Commodity Flow Problem in conjunction with the Constrained Shortest Path. Specifically, the ILP finds the shortest path between source and destination taking into account both network constraints and service requirements in terms of packet loss and delay for guaranteeing a QoS in SDNs. Moreover, the QoS architecture gives us the possibility to map the optimal solution provided by the mathematical model to various levels of QoS based on a well-known QoE metric called Mean Opinion Score (MOS) [4]. To make the tests possible, we define a multiple path topology composed of a wired and wireless network with also real mobile devices in order to be as close as possible to a real environment. We also test our proposal putting into the simulation different values of packet loss evaluating the impact of that on the user perception (QoE). Performance evaluation results, collected from the Mininet network emulator [5], confirm the benefits of our resource management architecture in providing QoS/QoE support for differentiated services in SDNs compared to the traditional solution. The simulations also remark that by means of our QoS architecture, it is possible to handle the network con- 978-1-4799-6959-3/15/$31.00 ©2015 IEEE 2015 International Conference on Computing, Networking and Communications, Communication QoS and System Modeling Symposium 505