Mitigating Elephant Flows in SDN-Based IXP Networks Luis Augusto Dias Knob *‡ , Rafael Pereira Esteves *† , Lisandro Zambenedetti Granville * , Liane Margarida Rockenbach Tarouco * * Institute of Informatics – Federal University of Rio Grande do Sul Av. Bento Gonc ¸alves, 9500 – Porto Alegre, Brazil † Federal Institute of Rio Grande do Sul - Campus Restinga Rua Alberto Hoffmann, 285 – Porto Alegre, Brazil ‡ Federal Institute of Rio Grande do Sul - Campus Sertao Rodovia RS 135, Km 25 – Sertao, Brazil Email: {luis.knob, rpesteves, granville}@inf.ufrgs.br, liane@penta.ufrgs.br Abstract—Internet Exchange Points (IXPs) play a key role in the Internet architecture, enabling cost-effective connections among multiple autonomous systems (ASes). The management of IXP networks includes the activity of taking care of elephant flows; they represent a small number of the total flows of an IXP, but have high impact on the overall network traffic. Managing elephant flows involves adequate identification and eventually rerouting of such flows to more appropriate locations, to minimize the possible negative impact on the other (mice) flows. Elephant flow management becomes even more important in SDN-based IXPs that require controllers to have a consistent view of the underlying network to allow fine-grained adjustment. In this paper, we propose, develop, and evaluate a recommendation sys- tem to suggest alternative configurations to previously identified elephant flows in an SDN-based IXP network. In our solution, the IXP operator can define templates that ultimately define how elephant flows can be rerouted to achieve a specific objective. We demonstrate that our system can help IXP operators to mitigate the impact of elephant flows on the IXP network. Keywords-Software Defined Networking, Internet Exchange Points, Network Management I. I NTRODUCTION Accounting for at least 20% of all traffic exchanged among Autonomous Systems (ASes), Internet Exchange Points (IXPs) play a critical role in the Internet ecosystem, both with regards to the communication between different parties (e.g., content providers, CDNs, ISPs), and in the relation between content providers (such as Google [1], Facebook [2], and Netflix [3]) and end-users [4]. Recently, a number of solutions for IXP management based on Software-Defined Networking (SDN) has been proposed, mainly to overcome the difficulties inherent to the Border Gateway Protocol (BGP) [5] and to instantiate functionalities that were hard or even impossible before, such as application-specific peering [6], inbound traffic engineering [7], wide-area server load balancing [8], and upstream block- ing of DoS attacks [9] [10]. Usually entirely based on layer-2 switches, IXP networks can be as complex as a single device or present quite intricate topologies too [11]. In such networks, identification of the so-called elephant flows [12] is critical to assist the IXP operator to, for example, spot links that form bottlenecks and, through the IXP’s SDN controller, engineer the network load by moving elephant flows from their original busier paths to more appropriate ones. Although several works present solutions for elephants flows identification [13] [14] [15], only a few develop methods to handle these flows along the network [7]. According to our knowledge, there is no solution today to manage elephant flows in IXP networks by exploiting SDN benefits. In this paper, we introduce an SDN-based IXP manage- ment solution that enables the IXP operator to define how to distribute elephant flows along the IXP network. In a previous work [16], we exploited how sFlow and OpenFlow can be used to snapshot the IXP network to identify the current elephant flows. In this paper, we enable the network operator to handle the identified elephant flows by using SDN rules. Our solution includes a recommendation system that, by employing templates (e.g., Optimize Links Consumption, Quality of Service, and Discard Packages) assists the IXP operator in the mitigation of elephants flows effects over his/her IXP. Our recommendation system suggests SDN rules over the IXP network that can be tuned by the operator, thus delivering a refined yet human-centered control loop. The remainder of this paper is organized as follows. In Section 2, we discuss some relevant concepts and review related work on the management of elephant flows in both traditional and SDN networks. In Section 3, we present our proposed solution and report on the implementation of an associated system prototype. Our solution is then evaluated in Section 4. We finally close this paper presenting concluding remarks and future work in Section 5. II. BACKGROUND AND RELATED WORK In this section, we review the main concepts related to our work, focusing on the management of IXPs and on the use of SDN in IXP management. Then we present and discuss some prominent related work in the area. 2017 IEEE Symposium on Computers and Communications (ISCC) 978-1-5386-1629-1/17/$31.00 ©2017 IEEE