| STP type | Standard | What it does | Where it’s used | Why it’s used |
|---|---|---|---|---|
| PVST | Cisco (proprietary) | One STP instance per VLAN | Older Cisco environments | Load balancing between VLANs |
| PVST+ | Cisco | One instance per VLAN + compatible with 802.1D/CST | Cisco networks with third-party switches | VLAN-based STP without compatibility problems |
| Rapid PVST+ | Cisco | PVST+ + RSTP (802.1W) | Modern Cisco networks | Fast convergence + per-VLAN control |
| CST | IEEE 802.1Q | One STP instance for all VLANs | Simple / small networks | Low complexity |
| RSTP | IEEE 802.1W | Fast STP with sync mechanism | All networks | Fast convergence |
| MST | IEEE 802.1s | Multiple VLANs per STP instance | Large networks | Scalability & performance |
Exam memory rule
PVST = per VLAN, MST = VLAN groups
Traps ⚠️
- Thinking PVST is a standard (it’s Cisco proprietary)
- Thinking MST is faster than RSTP (it’s merely more scalable)