PortFast feature should be used only to connect a single workstation to a switch port to avoid layer 2 switching loop. Spanning Tree PortFast feature causes a port to enter the forwarding state immediately, bypassing the listening and learning states.

When should I enable PortFast?

Any port that is directly connected to an end station cannot create bridging loops. Therefore, the port can rapidly transition to the forwarding state by skipping the learning and listening states. To enable immediate transition into the forwarding state, you can enable the STP portfast feature.

What is spanning-tree PortFast used for?

The PortFast feature is introduced to avoid network connectivity issues. These issues are caused by delays in STP enabled ports moving from blocking-state to forwarding-state after transitioning from the listening and learning states.