What mechanism does Ethernet use to detect changes in network topology?

Ethernet employs the Spanning Tree Protocol (STP) to detect and manage changes in network topology. STP is crucial for preventing loop conditions in networks that contain redundant paths. When a change occurs—such as a switch being added or removed—STP recalculates the network topology to ensure there are no loops and that data packets can still be efficiently routed from one switch to another.

This recalculation involves electing a root bridge and determining the best paths from this root bridge to all other switches in the network. By blocking redundant paths and allowing only a single active path to a destination, STP maintains a loop-free environment. If changes occur, STP reruns its calculation process, ensuring that the network remains stable and functional.

Other mechanisms listed, such as link aggregation, frame check sequence, and MAC filtering, serve different purposes in a network. For instance, link aggregation combines multiple network interfaces into a single logical interface for increased bandwidth; frame check sequence is used for error detection in frame transmission; and MAC filtering restricts network access based on device MAC addresses. These functions are important but do not specifically address the detection and management of topology changes in an Ethernet Network.