Software defined network (SDN) enables network programmability and provides fine grained control for managing the complex network infrastructure. With the centralized nature of SDN it poses the requirement for failure management at the data plane, control plane and at the centralized controller side. The self-healing attribute of the autonomic network can be combined with SDN to develop a software defined self-healing resilient network. The aim of this paper is to propose a self-healing SDN framework which can optimize the recovery by applying autonomic principles. The proposed work includes a rapid recovery (RR) mechanism to perform an immediate link recovery at the switch level without overburdening the controller. Additionally, it reduces the memory requirement of the switch for storing the backup path flow rules by aggregating all the disrupted flows. We presented the analytical model for calculating the failure recovery time and the backup flow rules required for recovery. Based on the analytical model, RR scheme reduces the total number of backup flow rules for all the disrupted flows of the failed link to a single flow rule.

Message broadcasting is an essential and widely-used operation in multi-hop Wireless Sensor Networks (WSNs). Minimum latency broadcast scheduling (MLBS) aims to achieve a schedule to broadcast messages with a minimum latency. In duty-cycle networks, a node alternates between active and sleep states, which causes decrease in energy consumption at the cost of increased broadcast latency. An existing scheme mathematically remodels the MLBS problem for duty-cycled WSNs and proposes a vector integration algorithm to solve the problem. In this paper, we propose a broadcast scheduling scheme by first finding critical-paths in a duty-cycled WSN. By scheduling transmissions with a preference of nodes in the critical-path, the proposed scheme reduces the broadcast latency as shown in the simulation results.

Minimum latency scheduling has arisen as one of the most crucial problems for broadcasting in duty-cycled Wireless Sensor Networks (WSNs). Typical solutions for the broadcast scheduling iteratively search for nodes able to transmit a message simultaneously. Other nodes are prevented from transmissions to ensure that there is no collision in a network. Such collision-preventions result in extra delays for a broadcast and may increase overall latency if the delays occur along critical paths of the network. To facilitate the broadcast latency minimization, we propose a novel approach, critical-path aware scheduling (CAS), which schedules transmissions with a preference of nodes in critical paths of a duty-cycled WSN. This paper presents two schemes employing CAS which produce collision-free and collision-tolerant broadcast schedules, respectively. The collision-free CAS scheme guarantees an approximation ratio of (Δ-1)T in terms of latency, where Δ denotes the maximum node degree in a network. By allowing collision at noncritical nodes, the collision-tolerant CAS scheme reduces up to 10.2 percent broadcast latency compared with the collision-free ones while requiring additional transmissions for the noncritical nodes experiencing collisions. Simulation results show that broadcast latencies of the two proposed schemes are significantly shorter than those of the existing methods.