What is a key characteristic of BPDU Filter when enabled globally?

When BPDU Filter is enabled globally, it specifically affects the interfaces that have PortFast enabled. This feature is designed to prevent BPDUs from being sent or received on access ports where PortFast is configured. By filtering BPDUs, it effectively makes these ports act as "edge ports," preventing them from participating in the Spanning Tree Protocol (STP) process.

This behavior is particularly critical for access ports connected to end devices, like computers and printers, where it is not expected to have switches connected that would generate BPDUs. By applying the BPDU Filter only to interfaces with PortFast enabled, the network can maintain optimal performance and stability by ensuring that end devices do not inadvertently cause STP topology changes.

In contrast, enabling BPDU Filter globally without this focus could disrupt STP functions across all interfaces, potentially leading to network loops or other unintended disruptions in the network topology. Hence, the targeted approach of applying BPDU Filter only to PortFast-enabled interfaces demonstrates its key characteristic.