Cisco ENCOR Practice Exam 2025 – All-in-One Comprehensive Guide to Mastering Enterprise Network Core Technologies!

In the context of the Spanning Tree Protocol (STP), particularly with Rapid Spanning Tree Protocol (RSTP) as defined by 802.1w, a port state that indicates a switch port is enabled but not forwarding is termed "Discarding."

When a port is in the Discarding state, it actively receives and processes BPDUs (Bridge Protocol Data Units) to maintain the topology but does not forward frames to reduce the potential for network loops. This is in contrast to the Forwarding state, where the port actively forwards traffic, and the Learning state, where the port is learning MAC addresses but still not forwarding frames. The Blocking state, meanwhile, is associated with the traditional Spanning Tree Protocol (802.1D) and serves a purpose similar to Discarding but involves a different set of considerations regarding root ports and designated ports within the 802.1D framework.

Thus, in the context of 802.1w, the Discarding state is essential as it plays a critical role in preventing loops while still allowing for rapid convergence in the case of topology changes.