As SDN migrates to wide area networks and 5G core networks, a scalable, highly reliable, low latency distributed control plane becomes a key factor that differentiates operator solutions for network control and management. In order to meet the high reliability and low latency requirements under time-varying volume of control traffic, the distributed control plane, consisting of multiple controllers and a combination of out-of-band and in-band control channels, needs to be managed dynamically. To this effect, we propose a novel programmable distributed control plane architecture with a dynamically managed in-band control network, where in-band mode switches communicate with their controllers over a virtual overlay to the data plane with dynamic topology. We dynamically manage the number of controllers, switches, and control flows assigned to each controller as well as traffic over control channels achieving both controller and control traffic load-balancing. We introduce “control flow table” (rules embedded in the flow table of a switch to manage in-band control flows) in order to implement the proposed distributed dynamic control plane. We propose methods for off-loading congested controllers and congested in-band control channels using control flow tables. A validation test-bed and experimental results over multiple topologies are presented to demonstrate the scalability and performance improvements achieved by the proposed dynamic control plane management procedures when the controller CPU and/or availability or throughput of in-band control channels becomes bottlenecks.

OpenFlow is a programmable network protocol and associated hardware designed to effectively manage and direct traffic by decoupling control and forwarding layers of routing. This paper presents an analytical framework for optimization of forwarding decisions at the control layer to enable dynamic Quality of Service (QoS) over OpenFlow networks and discusses application of this framework to QoS-enabled streaming of scalable encoded videos with two QoS levels. We pose and solve optimization of dynamic QoS routing as a constrained shortest path problem, where we treat the base layer of scalable encoded video as a level-1 QoS flow, while the enhancement layers can be treated as level-2 QoS or best-effort flows. We provide experimental results which show that the proposed dynamic QoS framework achieves significant improvement in overall quality of streaming of scalable encoded videos under various coding configurations and network congestion scenarios.

This paper proposes a new Quality of Service (QoS) optimized routing architecture for video streaming over large-scale multi-domain OpenFlow networks managed by a distributed control plane, where each controller performs optimal routing within its domain and shares summarized intra-domain routing data with other controllers to reduce problem dimensionality for calculating inter-domain routing. We apply the proposed architecture to streaming of scalable (layered) videos, where the base layer routes are dynamically optimized to fulfill a required QoS level, while enhancement layers follow traditional shortest path. We show that the proposed solution approaches the expensive non-scalable globally optimal solution (single controller for the whole network) in terms of received video quality under various congestion scenarios.

OpenFlow is a clean-slate Future Internet architecture that decouples control and forwarding layers of routing, which has recently started being deployed throughout the world for research purposes. This paper presents an optimization framework for the OpenFlow controller in order to provide QoS support for scalable video streaming over an OpenFlow network. We pose and solve two optimization problems, where we route the base layer of SVC encoded video as a lossless-QoS flow, while the enhancement layers can be routed either as a lossy-QoS flow or as a best effort flow, respectively. The proposed approach differs from current QoS architectures since we provide dynamic rerouting capability possibly using non-shortest paths for lossless and lossy QoS flows. We show that dynamic rerouting of QoS flows achieves significant improvement on the video's overall PSNR under network congestion.

A failure detection strategy at the data-link layer, implementable between frame-relay network nodes, is described for integrated voice/data packet networks. This strategy makes it possible to respond to link failures early enough to maintain data-session continuity. A simple, two-phase approach is proposed. In the first phase, the presence of a bit error rate violation along the packet link during short, fixed-length time segments is determined. In the second phase, the failure decision is made on the basis of a sequential algorithm. A simple table lookup implementation of the algorithm that requires no real-time computation is described.>