How does RSTP (Rapid Spanning Tree Protocol) improve upon traditional STP (Spanning Tree Protocol)?

RSTP (802.1w) achieves convergence in milliseconds instead of 30-50 seconds by using active negotiation instead of passive timers.

Key improvements:

• Same algorithm — RSTP uses the same STA (Spanning Tree Algorithm) to determine topology, so the concepts of root bridge, root ports, and designated ports remain
• Backward compatible — works alongside legacy STP devices
• Dramatically faster convergence — can converge in as little as a few hundred milliseconds in a properly configured network

How it's faster:

• STP passively waits through listening (15s) + learning (15s) = 30 seconds minimum
• RSTP uses proposal-agreement handshake between switches to rapidly transition ports to forwarding
• An alternate port can immediately become a root port without waiting for timers

Rapid PVST+ (Per-VLAN Spanning Tree Plus) is the Cisco implementation of RSTP on a per-VLAN basis — an independent RSTP instance runs for each VLAN (Virtual Local Area Network).

Go deeper:

• Rapid Spanning Tree (RSTP) (NetworkLessons) — contrasts timer-based 802.1D with 802.1w's proposal/agreement handshake, new port roles and much faster convergence.