Efficient Fiber Link Discovery Algorithm for Multi-Stage Optical Data Center Networks

The proliferation of data-intensive applications, such as generative AI, has substantially increased the demand for low-latency and energy-efficient data center networks (DCNs). Supporting these applications requires large-scale deployment of servers and GPUs, which in turn necessitates highly scalable DCNs. To meet these performance and scalability requirements, hierarchical optical DCNs leveraging optical circuit switches (OCSs) have emerged as a promising approach. The reliable operation of hierarchical OCS-based DCNs depends on accurate fiber-link topology information. However, topology discovery at the fiber layer is inherently challenging because OCSs operate transparently without signal processing or optical power monitoring capabilities. Although prior studies have investigated fiber-layer topology inspection methods for OCS-based DCNs, their applicability is limited to conventional duplex fiber-pair deployments and does not extend to (i) deployments employing bidirectional (Bi-Di) transmission over a single fiber core or (ii) deployments requiring per-core fiber management due to OCS constraints. To bridge this gap, we propose a fiber-link discovery (FLD) algorithm that correctly identifies unidirectional fiber topology in hierarchical OCS-based DCNs, requiring only O(h log2 L) discovery steps, where h is the number of stages and L is the number of fibers between each pair of adjacent-stage OCSs. Simulation results demonstrate that our algorithm achieves up to 341.3× faster topology identification than the baseline method while guaranteeing correctness.