Efficient Fiber-Inspection Method for Optical-Circuit Datacenter Networks

Data center networks (DCNs) consisting of optical-circuit switches (OCSes) have been intensively studied due to optical transmission's high capacity and energy efficiency. Since current DCNs consist of packet switches, the condition and cabling of optical fibers can be inspected easily by probing neighboring switches. However, OCS networks cannot be inspected in the same manner because OCSes only pass through optical signals. We have had to attach and detach a tester device to every switch for probing all the fibers, which is very time-consuming. This paper proposes a method for automatically inspecting fibers in an entire DCN without repeating tester reattachment. Our method is based on (1) theories on quickly estimating the fiber condition on the basis of the intensity of received probe signals and involves (2) an algorithm that reduces the number of probes needed. Numerical evaluation showed that our method can be used to inspect a huge DCN with 32,000 fibers in at most 2 days, whereas a baseline method involving repeated tester reattachment would take 2 weeks. An experiment using actual OCSes was also conducted to confirm the feasibility of our method.