Cross-layer Diagnosis of Optical Backbone Failures

Abstract

Optical backbone networks, the physical infrastructure interconnecting data centers, are the cornerstones of Wide-Area Network (WAN) connectivity and resilience. Yet, there is limited research on failure characteristics and diagnosis in large-scale operational optical networks. This paper fills the gap by presenting a comprehensive analysis and modeling of optical network failures from a production optical backbone consisting of hundreds of sites and thousands of optical devices. Subsequently, we present a diagnosis system for optical backbone failures, consisting of a multi-level dependency graph and a root-cause inference algorithm across the IP and optical layers. Further, we share our experiences of operating this system for six years and introduce three methods to make the outcome actionable in practice. With empirical evaluation, we demonstrate its high accuracy of 96% and a ticket reduction of 95% for our optical backbone.