Modeling and Emulation of Optical Networks for SDN Control

Abstract

Today's telecommunications networks are facing increasing internet traffic demands for a variety of high data-rate applications including virtual reality (VR), video-conferencing, and high-definition (HD) video streaming. Optical networks are more efficient than wired and copper networks over long distances and high speeds, and thus have been a large contributor for increasing data capacities over the past several decades. Developments in optical fiber technologies have allowed optical networks to be manufactured at steadily lower cost per bit. However networks do not just need to handle larger traffic volumes, they also need to work with existing network architectures and accommodate traffic requests with different requirements. One method for addressing this challenge is Software Defined Networking (SDN). SDN separates the control and data-plane so the data management and control decisions are made by a central controller that direct information as need be. However, developing SDN systems for optical networks at scale is difficult because optical networks need to consider signal quality and nonlinear fiber impairment. Mininet-Optical is an optical network emulator designed to emulate a multi-layer optical network so network designers can develop SDN control algorithms. Mininet is an open-source tool for studying SDN but does not support optical networks. We developed an optical layer simulator that is integrated into Mininet Optical. We evaluated this approach using the open-source planning tool GNPy and showed strong agreement. We also developed an SDN control algorithm for provisioning optical networks with bandwidth variable transceivers (BVTs) and examined how the SDN controller responds to diurnal traffic. BVT technology has received attention from the SDN community because of its ability to change modulation formats to optimize network capacity and their performance depends on the quality of transmission. This adds an extra element of control that SDN controllers can use to respond to varying traffic conditions such as diurnal traffic patterns and respond to different traffic needs. In this thesis we discuss SDN control, BVTs, Diurnal traffic modeling, optical fiber transmission physics, and the mininet optical system. From this, we will examine SDN control for a network with BVTs handling requests from metro networks in residential and office areas with diurnal traffic. This work shows how BVTs operate in an SDN controlled network while responding to time-varying traffic, and show non-linear impairment induced switching for heavily-loaded traffic.