Software Defined Wide Area Networking (SD-WAN)

A reliable Wide Area Network (WAN) has become a necessity for businesses to transmit critical data across multiple branches and to increase their revenues. Many solutions and dierent network structures have been proposed over years such as leased lines, Frame Relay or Multi-Protocol Label Switching Virtual Private Networks (MPLS VPN). Each solution is intended to be better than its predecessors in terms of reliabil- ity and Quality of Service (QoS). Software-Dened Wide Area Networking (SD-WAN) is an emerging paradigm that introduces the advantages of software dened networking (SDN) into enterprise networking. SD-WAN can support dierentiated services over pub- lic WAN by dynamically changing the ow forwarding rules over an overlay network based on monitoring data and service requirements. Thanks to these capabilities, it is possible to overcome high cost of guaranteed QoS services such as MPLS. Most of the SD-WAN so- lutions commercially available today are based on proprietary controllers and proprietary Customer Provider Edge (CPE) devises. In this chapter, we present an implementation of SD-WAN based on open source components such as OpenDaylight SDN controller and Open Virtual Switch (OvS). This work targets the monitoring features of an SD-WAN solution and explores active and passive monitoring approaches to understand their ad- vantages and limitations. Our implementation provides an overlay WAN with controlled performance in terms of delay and losses over low-cost Internet connectivity.