Applications of Software Defined Networking in a Service Provider Environment

Software Defined Networking (SDN) is a networking paradigm that promises to give network administrators finer control over the network, the ability to manage traffic flows effectively, and make re-provisioning network resources faster while also enabling the network to be more flexible, scalable and visible. Despite the promises and potential of SDN, the adoption of SDN by service providers is a challenging, daunting task and hence has not seen approval and acceptance. Although this lack of adoption can be attributed to a few major factors, an important limitation is that enterprise networks do not have a green-field environment and it is not viable to do an overhaul of the existing traditional network infrastructure to build an SDN-based network in its place. Additionally, other significant concerns such as cost, time, performance and security are also deciding factors in enabling SDN in a service provider environment. To facilitate the adoption of SDN in ISPs and a smoother transition, the concept of a Hybrid SDN/IP network has emerged. The fundamental idea behind this concept of a hybrid network is to invest in a few SDN-capable devices that will be incorporated into an existing, functional and operational legacy network. This simple idea has been seen as a promising migration strategy to enable SDN adoption in service provider networks. The goal of this thesis is to explore, identify and implement use case scenarios of such a hybrid network, in which, a few SDN devices co-exist within the traditional network architecture. To this end, we first present Inter-Autonomous System Traffic Engineering with SDN that takes advantage of the presence of SDN devices in the network to solve the Inter-AS TE problem in service provider networks. By introducing SDN elements in the internal network of an AS, we show how the stringency of the internal network can be overcome to better load balance traffic on the outgoing links of the network. Intuitively, identifying productive locations to place the SDN devices can effectively decrease the number of SDN devices required to achieve the objectives for the ISP. In keeping with this idea, we then explore the SDN node selection problem that addresses how to choose a set of nodes in the existing network that can be replaced by SDN devices in order to meet the objective for Inter-AS TE in an ISP. Lastly, we propose Greening service provider networks with SDN to address the problem of high energy consumption in service provider networks. We aim to leverage the presence of SDN nodes in the network to enable shutting down unused routers within the network. Although shutting down routers inside a network results in lower energy consumption of the network, we run the risk of having all the traffic traverse through only a few egress links in the network, thereby leading to congestion on these links. Thus, we propose to take advantage of the flexibility of SDN nodes in the network by being able to move traffic around to avoid congestion on the egress links, while at the same time enabling shutdown of nodes in the network. We believe that the ideas explored and presented in this thesis bring to perspective interesting solutions incorporating SDN to some of the problems seen in today’s traditional service provider networks. These solutions are based on adopting a transitional approach to incorporating SDN with the legacy infrastructure and add to the many potential benefits that the SDN paradigm promises for a service provider network.