Difference between Spanning Tree Protocol (STP) and Rapid Spanning Tree Protocol (RSTP)

• The main difference between Rapid Spanning Tree Protocol (RSTP IEEE 802.1W) and Spanning Tree Protocol (STP IEEE 802.1D) is that Rapid Spanning Tree Protocol (RSTP) assumes the three Spanning Tree Protocol (STP) ports states Listening, Blocking, and Disabled are same (these states do not forward frames and they do not learn MAC addresses). Hence RSTP places them all into a new called Discarding state. Learning and forwarding ports remain more or less the same.

• In Spanning Tree Protocol (STP IEEE 802.1D), bridges would only send out a BPDU when they received one on their root port. They only forward BPDUs that are generated by the Root Bridge. Rapid Spanning Tree Protocol (RSTP IEEE 802.1W) enabled switches send out BPDUs every hello time, containing current information.

• Spanning Tree Protocol (STP IEEE 802.1D) includes two port types; Root Port and Designated Port. Rapid Spanning Tree Protocol (RSTP IEEE 802.1W) includes two additional port types called as alternate ports and backup ports. An alternate port is a port that has an alternative path or paths to the root but is currently in a discarding state (can be considered as an additional unused root port). A backup port is a port on a network segment that could be used to reach the root switch, but there is already an active designated port for the segment (can be considered as an additional unused designated port).

Related Topics...

• What is Broadcast Storm

• What is Layer 2 Switching loop

• What is Bridge Protocol Data Unit (BPDU) frame

• Bridge Protocol Data Unit (BPDU) Frame Format

• What is a Root Bridge (Switch)

• What is a Root Port

• What are Port Cost, Port Priority and Path Cost Values

• How Spanning Tree Protocol (STP) select Root Port

• What is a Designated Port

• How Spanning Tree Protocol (STP) select Designated Port

• Difference between Root Port and Designated Port