Types of Spanning Tree Protocol
There are the following types of Spanning Tree Protocol –
1. Common Spanning Tree (802.1D)
A Common Spanning Tree (802.1D) standard is developed by IEEE which elects only one Root Bridge for the whole topology. 802.1D uses blocking, listening, learning, and forwarding states.
It is very slow. It takes 32 seconds to the convergence.
Advantage:
It requires less memory and CPU utilization.
Disadvantages:
- It does not support load balancing.
- Slow convergence
2. Pre VLAN Spanning Tree+ (PVST+)
Pre VLAN Spanning Tree+ (PVST+) is developed by the Cisco. This Protocol provides support to the IEEE 802.1Q trunking. It provides a separate 802.1d spanning tree instance for each VLAN configured in the network. The separate instance supports UplinkFast, PortFast, BackboneFast, BPDU filter, BPDU guard, root guard, and loop guard.
Advantages
- PVST+ allows optimum load balancing.
- Less bandwidth consumption as compare to Common Spanning Tree.
Disadvantages
- PVST+ requires more resources (CPU and memory)
- Slow convergence
3. Rapid Spanning Tree Protocol (RSTP) 802.1w
Rapid Spanning Tree Protocol (RSTP) standard is developed by IEEE, which provides faster convergence. It uses discarding, learning, and forwarding states.
RSTP mainly uses two designation ports –
- Alternate Port – It provides backup for the root port
- Backup Port – It provides backup for the designated port on the segment.
Advantages
- In RSTP, all the bridges send BPDUs automatically.
- Faster Convergence.
4. Rapid Per VLAN Spanning Tree+ (RPVST+)
Rapid Per VLAN Spanning Tree+ (RPVST+) is developed by the Cisco, which provides faster convergence than PVST+. RPVST+ provides a separate instance of 802.1w per VLAN. The separate instance supports BPDU guard, PostFast, BPDU filter, loop guard, and root guard.
Advantage
Fast Convergence
Disadvantages
RPVST+ requires more resources (CPU and memory)
A summary of Types of Spanning tree protocols is given below table:
| Type of STP | Standard | Resources Needed | Convergence | Number of Trees |
| STP | 802.1D | Low | Slow | One |
| PVST+ | Cisco | High | Slow | One for every VLAN |
| RSTP | 802.1w | Medium | Fast | One |
| RPVST+ | Cisco | Very high | Fast | One for every VLAN |