What is Spanning Tree Protocol (STP)?

STP (Spanning Tree Protocol) is a network protocol defined by the IEEE 802.1D standard to prevent network loops by ensuring there is only one active path between devices in redundant network topologies. STP uses BPDU (Bridge Protocol Data Units) to exchange information and determine the best path for data. If the primary path fails, STP reconfigures the network, activating a backup path and maintaining network stability.

Example Scenario: Multiple switches used for redundancy in a SCADA network.

When a SCADA system has several HMI and PLC devices connected to switches for monitoring and control, enabling STP ensures that if a switch or path fails, traffic will automatically reroute through another path without causing loops. This keeps the network stable and prevents broadcast storms, ensuring continuous data flow between devices. Without STP, redundant links could form loops, leading to network instability and downtime.

Content created by Mike Day