Can a blocking interface move directly to a forwarding state?

In the context of the Spanning Tree Protocol (STP), a blocking interface cannot move directly to a forwarding state. Instead, it must go through a series of states: listening, learning, and then finally, forwarding. This gradual progression is crucial because it helps ensure that there are no network loops generated as the topology changes.

When an interface is in a blocking state, it is effectively disabled for the purpose of forwarding traffic. This state prevents data frames from being sent or received, ensuring that potential loops do not disrupt the network. During this time, STP algorithms are actively listening and learning about the network topology before allowing an interface to transition to a forwarding state.

Although PortFast allows certain interfaces to skip the listening and learning states to quickly transition into a forwarding state, it only applies to interfaces that are directly connected to end devices (like workstations or servers) and not to switch-to-switch links. In the case of a typical switchport configured for STP, without PortFast, the default behavior will always involve moving through the appropriate sequence of states to maintain network integrity.