Hands-On Lab: Enabling Rapid Per-VLAN Spanning Tree (RPVST+)

Lab Objective

Change a switch's Spanning Tree mode from classic PVST+ to Rapid PVST+, verify the mode change took effect, and compare convergence time on a port before and after the change.

Lab Purpose

Classic 802.1D Spanning Tree, used by default in PVST+, takes up to 50 seconds to converge after a topology change, as observed in earlier labs. Rapid PVST+ (based on 802.1w) achieves convergence in seconds rather than tens of seconds, making it the standard choice in virtually all modern network deployments.

Lab Topology

Switch1 ---- Gi1/0/5 ---- Switch2
Switch1 ---- Gi1/0/6 ---- Switch2 (redundant link)

Both switches currently running default
PVST+ mode

Task 1: Verify Current Spanning Tree Mode

Confirm both switches are currently running classic PVST+.

Task 2: Enable Rapid PVST+

Change the Spanning Tree mode to rapid-pvst on both switches.

Task 3: Verify the Mode Change

Confirm both switches now show rapid-pvst as the active mode.

Task 4: Compare Convergence Time

Shut down and re-enable the forwarding link, then time how quickly the blocking link transitions to forwarding, comparing this against the 30-50 second delay observed under classic PVST+ in an earlier lab.

Task 5: Observe Updated Port Role Terminology

Note any differences in how port roles are displayed under Rapid PVST+.

Solution and Verification

Switch1# show spanning-tree summary | include Mode

Spanning tree enabled protocol ieee
-- "ieee" indicates classic 802.1D PVST+

Switch1(config)# spanning-tree mode rapid-pvst
Switch2(config)# spanning-tree mode rapid-pvst

Switch1# show spanning-tree summary | include Mode

Spanning tree enabled protocol rstp
-- Confirms Rapid PVST+ (based on RSTP, 802.1w)
-- is now active

Switch1(config)# interface gigabitethernet1/0/5
Switch1(config-if)# shutdown
Switch1(config-if)# no shutdown

Switch1# show spanning-tree vlan 1
-- checked repeatedly: the previously blocking
-- link (Gi1/0/6) transitions to forwarding
-- within roughly 1-6 seconds, dramatically
-- faster than the 30-50 seconds observed
-- under classic PVST+ in the earlier root
-- bridge lab

Switch1# show spanning-tree vlan 1

Interface     Role  Sts  Cost   Prio.Nbr  Type
Gi1/0/5       Desg  FWD  4      128.5     P2p
Gi1/0/6       Root  FWD  4      128.6     P2p
-- Notice the port role naming remains
-- consistent (Root, Designated, Alternate),
-- though RSTP's internal state machine that
-- achieves this transition so quickly is
-- fundamentally different from classic STP

Key Takeaway

Rapid PVST+ dramatically reduces convergence time compared to classic PVST+ while keeping the same familiar per-VLAN priority and port role concepts covered in earlier labs — this makes migrating an existing PVST+ network to Rapid PVST+ a low-risk, high-value change, since it is largely a mode switch rather than a redesign of the underlying VLAN and priority configuration.