OpenFlow data planes performance evaluation

Abstract

Software-Defined Networks, in its essence, are the separation of the data and control planes of switching devices. The OpenFlow (OF) protocol is the most popular SDN protocol today, being available in many switches. This is due to the low implementation cost as well as the potential for innovative solutions in the network. Although OF is being used in many research papers and production networks, as far as we know, no work on the literature performs an extensive evaluation of the OpenFlow data planes. This evaluation helps network administrators choose which switch to use in their networks. Meanwhile, researchers are made aware of the limitations of existing OF switches. This article evaluates the performance and maturity of OF 1.0 on eleven hardware and software switches using POX, and also of the newer OF 1.3 on five switches using the ONOS controller. Our findings indicate that the performance variations among OF switches are significant. Packet delays vary by one order of magnitude in the evaluated equipment. Meanwhile, there is no performance impact when changing the packet size. Hence, the results highlight that researchers must be aware of issues such as variable jitter, the number of matches in tables as well as missing OF match fields.

Introduction

Software-Defined Networking (SDN) is a technology that is reshaping the way networks are operated and developed [1]. SDN simplified the creation of new networking solutions, mainly because of the separation of the data and control planes. The key benefits of this are the fast deployment of new services, which drive down the costs of network operators. Because of that, SDN is becoming a key architecture component on 5G systems [2]. SDN can even be used to support matching rules with domain names [3]. Furthermore, researchers are now able to perform tests in real environments, without affecting the traffic or the availability of production networks [1]. In this context, there is no doubt that the SDN paradigm attracted attention from both academia and industry.

There are several sophisticated SDN implementations, such as P4 (Programming Protocol-independent Packet Processors) and POF (Protocol-oblivious Forwarding) [4], [5]. However, OpenFlow is the most popular standard in production networks and research. This occurs because vendors can implement OpenFlow without significant difficulties.

Despite being widely employed in industry and academia, as far as we know, no work has evaluated the existing OpenFlow data planes. Such a study is important for operators because it provides an assessment that may guide the deployment of OpenFlow on their network. For researchers, this is useful to grasp the limitations of OpenFlow in current hardware. With this information in mind, better emulators and simulators can be built, by representing the performance and features of those switches more realistically. Many papers evaluate the performance of the OpenFlow Controllers [6], [7], [8], [9], however, most of them do not measure how the implementation of the data plane affects the network performance. Only [7], [8], [9] evaluate the data plane, however, their work does not measure the data plane separately from the control plane. It is important to properly investigate the data plane because the performance of the controller only affects the first packet in a flow. The data plane, however, will define the performance for the entire flow.

Given this context, this article evaluates the performance and maturity of the main features of OpenFlow 1.0 and 1.3 on both hardware and software switches. We consider a wide number of switches, varying from various off-the-shelf equipment to open source implementations of software switches running on PCs or embedded platforms (e.g. home routers). In a controlled environment, we systematically evaluate the implementation of the OpenFlow data planes by: (i) measuring the performance of the switch in terms of latency and jitter, (ii) assessing how the OpenFlow mode compares to the legacy L2 switching mode, and (iii) evaluating how OpenFlow operations (such as rule matches, packet rewrites, flowstats, and packetstats reports) perform. This article extends our previous work [10]¹ by:

• Adding OpenFlow 1.3 performance evaluation experiments;

• Adding one more commercial switch to the comparison of OpenFlow 1.0 switches (Zodiac FX);

• Testing a highly optimized version of Open vSwitch using the Intel DPDK suite of Linux kernel modifications, to understand how OS optimizations may improve the performance of software switches;

• Adding high-performance switch evaluation;

Our results show that OpenFlow’s performance varies significantly. For example, packet delays vary by one order of magnitude among the evaluated switches, while the performance is not affected by the packet size. Moreover, we also note that some hardware switches perform as well as software switches, which may indicate a software implementation within the hardware. In sum, our article presents a glimpse into how OpenFlow is currently implemented on real devices. This is important for network administrators and academics to understand how OF switches work, allowing them to pick the best switch for their network.

The remainder of this article is structured as follows. Section 2 presents related work. Section 3 describes the evaluation methodology. Sections 4 Results for OpenFlow 1.0, 5 Results for OpenFlow 1.3 discuss the results for OpenFlow 1.0 and OpenFlow 1.3, respectively. Section 6 concludes the article and presents future work.