How do you design SCADA communication architecture for distributed sites?

Distributed SCADA communication design: assess bandwidth requirements (polling rates, point counts), select media (radio, cellular, fiber, satellite) based on distance and terrain, design for redundancy (dual paths), implement store-and-forward for unreliable links. Architecture options: centralized polling from master, hierarchy with intermediate concentrators, or peer-to-peer reporting by exception. Address latency requirements, cybersecurity (encryption, authentication, firewalls), and remote diagnostic access. Test communication reliability during commissioning. Consider MQTT for IoT applications and DNP3 for utility SCADA.