Managing resilience in carrier grade networks: Survey, open issues and trends.

IP/MPLS and Optical technologies are the foundations of current Carrier-Grade Networks (CGNs), due to both the flexibility of IP/MPLS to provide services with distinct requirements and the high transport capacity offered by new Optical technologies, such as Elastic Optical Networks (EONs). However, despite the widespread adoption of these two technologies, interoperability issues still impact on key network features, in particular on resilience capabilities. Resilience is gaining momentum in recent years due to the advent of new CGN scenarios, such as Data Center Networks (DCNs), where a link or a node failure might lead to a substantial traffic loss. We consider that any potential contribution on the resilience arena, must be built on top of a solid knowledge of available proposals emphasizing most appealing research trends and the limitations affecting the management of resilience in CGNs. Aligned to this scenario, the main goals of this article are: (1) compile distinct approaches for managing resilience; (2) describe in a comprehensive manner, the challenges faced by CGN operators in order to manage resilience; (3) show why current solutions for managing resilience do not completely address the interoperability issues present in multi-layer CGNs with multi-vendor settings, and; (4) provide insights for future trends.