Rule-Based Automation of FTTH/GPON Design Changes: Synchronized Fiber Routing and Allocation across CAD and Spreadsheet Workflows

Fiber-to-the-home (FTTH) design workflows still contain repetitive engineering operations that require designers to propagate fiber-allocation changes across multiple records and drawing layers. This paper presents an industry-informed, rule-based automation tool for a recurring Gigabit-capable Passive Optical Network (GPON) work-order task: updating fiber routing and allocation from a target distribution joint toward the central office while generating synchronized outputs for spreadsheet-based allocation records and AutoCAD-based engineering drawings. The study combines practitioner evidence with design-and-build research. An online survey of 25 FTTH design professionals identified manual end-to-end fiber modification as the most frequently selected time-consuming task, accounting for 52% of responses. The resulting prototype accepts work-order, joint, splitter, routing-mode, and output parameters; applies deterministic engineering rules along the relevant network path; and produces traceable Excel and AutoCAD updates. Functional validation uses a representative 107-premises GPON scenario requiring 30 fiber connections and upstream capacity changes. The prototype successfully exercised the complete parameter-to-output workflow, including path propagation, allocation-table modification, CAD annotation, and work-order traceability. The work demonstrates a practical automation layer for brownfield FTTH engineering changes that complements topology-optimization approaches focused on greenfield network planning.