CFR: A cooperative link failure recovery scheme in software-defined networks.

Software-defined networking that separates the control plane from the data plane is envisioned as a promising technology to enable resilient and flexible network management. Tolerating link failures is a fundamental problem in enhancing such network resilience in software-defined networking. Reactive and proactive fault tolerant schemes for conventional networks may not well balance the fault recovery time and network performance, since the proactive scheme typically underutilizes resources and the reactive scheme usually incurs a longer recovery time. In this paper, we propose a cooperative link failure recovery scheme to find a fine-grained trade-off between resource utilization and recovery time by combining reactive and proactive methods. We formalize the problem of link failure recovery as a multiobjective optimization problem and devise a 2-stage algorithm for it. The first stage of the algorithm guarantees connectivity restoration in an acceptable recovery interval based on fast failover feature supported in OpenFlow protocol, meanwhile it assigns virtual local area network tags to back up paths for achieving a lower memory consumption. The second stage of the algorithm guarantees the quality of service for different applications by adjusting the backup paths after rapid connectivity restoration. Extensive simulations highlight that cooperative link failure recovery scheme can satisfy both the carrier-grade recovery requirements and quality of service requirements in terms of delay and network bandwidth. [ABSTRACT FROM AUTHOR]