TY - JOUR TI - The design and evaluation of a hierarchical OpenFlow SDN control plane DO - https://doi.org/doi:10.7282/T3KW5D23 PY - 2013 AB - This thesis investigates the design of hierarchical software-defined networks with improved scalability and service integration. Software Defined Networking (SDN) aims to bring flexibility and intelligence into networks by moving the network stack into logically centralized, programmable control planes. While distribution schemes and virtualization have addressed control plane scalability and network stack coexistence, they do so separately as unrelated subjects, and no unified solution exists. This work addresses the intersection of the two aspects through a little-explored control plane distribution method in which controllers are organized into a hierarchy based on service characteristics. Specifically, this thesis addresses 1) the evolution of SDN control plane architectures, focusing on distributed SDNs based on the OpenFlow SDN control protocol, and 2) the design, implementation, and evaluation of an architecture for a hierarchical OpenFlow control plane. A layered model for control plane architecture is presented as a reference for the design. The widely-adopted Floodlight SDN framework is used to implement a prototype. The prototype is implemented as a series of modules that extend the base platform to use an OpenFlow-based inter-controller protocol. This protocol enables controllers to configure one another based on their positions in the hierarchy, enabling them to coordinate event handling by the network services at each controller. This prototype is evaluated on the wired sandboxes of the ORBIT network testbed, with focus on control plane overhead and scalability. A custom OpenFlow client is used to measure processing overheads for several control plane topologies. Scalability is evaluated with respect to event processing rate at the lowest tier, and the amount of requests received at the upper tiers, of a sample hierarchy. Each controller involved in event handling is found to add at most about 0.46ms to overhead per packet, discounting network link delays. A comparison with the stock controller reveals that the control plane scales in event processing capacity with the number of data plane-facing controllers, and that the volume of requests at higer tiers are coupled to the types of events requested. We finish with remarks on potential future improvements to the control plane design. KW - Electrical and Computer Engineering KW - Software engineering KW - Computer software--Development KW - Hierarchical routing (Computer network management) LA - eng ER -