What is the purpose of a trunk port on a switch?

The purpose of a trunk port on a switch is to carry traffic for multiple VLANs over a single link. In a switched network, VLANs (Virtual Local Area Networks) are utilized to segment traffic for different groups or departments. A trunk port allows for the transmission of traffic from multiple VLANs, which means it can encapsulate VLAN information using protocols like IEEE 802.1Q. This is crucial for maintaining the integrity and separation of VLAN traffic as it passes between switches and across a network, ensuring that devices in different VLANs can communicate effectively while still being segmented.

In comparison, connecting switches in a star topology primarily involves access ports and does not specifically relate to the trunking concept. While isolating devices from one another could relate to VLANs, it is not the primary function of a trunk port. Similarly, extending the range of a single VLAN does not accurately describe how trunk ports function, as trunk ports are meant to facilitate multiple VLANs rather than just one.