Network Strategy in Mainframe Modernization From Legacy to Cloud

Mainframes continue to host critical transaction processing for banking, insurance, retail, travel, and public‑sector workloads. At the same time, organizations want the elasticity, speed of delivery, and AI capabilities of public cloud platforms. Modernization initiatives therefore often adopt a phased approach in which mainframe systems of record coexist with newly built cloud‑native applications. In this context, network strategy becomes a first‑class concern: it determines how data and services are exposed, how securely traffic flows between on‑premises and cloud, and how resilient the hybrid environment is during this multi‑year migration and modernization journey. This paper provides a concise overview of hybrid connectivity options for mainframe modernization, including VPN, dedicated private connectivity, and SD‑WAN‑based designs. It discusses security and reliability patterns, identifies gaps in current guidance, and proposes a research design to generate data‑driven recommendations. The goal is to help architects choose network strategies that reduce migration risk while preserving mainframe strengths such as security, availability, and predictable performance.