What is the function of the Spanning Tree Protocol (STP)?

The function of the Spanning Tree Protocol (STP) is fundamentally to prevent broadcast storms and ensure a loop-free topology within Ethernet networks. When there are multiple paths between network switches, the risk of creating loops that can congest the network or cause broadcast storms increases. STP helps by detecting these redundant paths and selectively disabling one or more of them, effectively establishing a single active path and blocking the others.

By implementing this protocol, when a switch receives a broadcast frame, it can do so without the danger of the frame endlessly circulating in the network. This capability is crucial for maintaining optimal network performance and reliability. When a trunk line is disabled, it stops the potential loop and thereby the continuous repetition of broadcasts, which could overwhelm the network traffic.

In contrast, the other options do not accurately reflect the primary function of STP. Prioritizing traffic, optimizing VLAN configurations, and managing Link Aggregation Groups are functions related to Quality of Service (QoS), VLAN management, and link aggregation, which do not address the root concern of preventing loops within the network structure like STP does.