When the network crumbles: an empirical study of cloud network failures and their impact on services

The growing demand for always-on and low-latency cloud services is driving the creation of globally distributed datacenters. A major factor affecting service availability is reliability of the network, both inside the datacenters and wide-area links connecting them. While several research efforts focus on building scale-out datacenter networks, little has been reported on real network failures and how they impact geo-distributed services. This paper makes one of the first attempts to characterize intra-datacenter and inter-datacenter network failures from a service perspective. We describe a large-scale study analyzing and correlating failure events over three years across multiple datacenters and thousands of network elements such as Access routers, Aggregation switches, Top-of-Rack switches, and long-haul links. Our study reveals several important findings on (a) the availability of network domains, (b) root causes, (c) service impact, (d) effectiveness of repairs, and (e) modeling failures. Finally, we outline steps based on existing network mechanisms to improve service availability.