Difference Between RSTP and PVST

The Rapid Spanning Tree Protocol (RSTP) and the Per-VLAN Spanning Tree Protocol (PVST) are protocols used in Ethernet networks to prevent loops and provide network connection redundancy.

RSTP is a Spanning Tree Protocol (STP) evolution that is designed to provide faster convergence times in response to changes in network topology. PVST is a Cisco proprietary protocol that creates a separate spanning tree for each VLAN using STP.

What is RSTP?

Rapid Spanning Tree Protocol (RSTP) is an evolution of Spanning Tree Protocol (STP) that allows for faster convergence times in response to changes in network topology. RSTP accomplishes this by using a more efficient algorithm for calculating network topology and providing faster port transition times.

RSTP works by selecting a root bridge, which is the central point of the spanning tree. It calculates the shortest path from the root bridge to each network segment and forwards or blocks each port based on whether it is on the shortest path to the root bridge.

Key Features of RSTP

• Rapid Convergence Algorithm Detects changes in the network topology and calculates the new spanning tree without waiting for the forwarding delay timer to expire.

• Edge Port Detection Allows ports to transition from blocking to forwarding without waiting for the forwarding delay time to expire.

• Backup Port Concept If a connection fails, the backup port can take over instantly without recalculating the spanning tree.

• Port Roles Allows administrators to prioritize specific ports and customize how RSTP selects the best path to the root bridge.

What is PVST?

Per-VLAN Spanning Tree (PVST) is a Cisco proprietary protocol that creates a separate spanning tree for each VLAN using the Spanning Tree Protocol (STP). This allows load balancing across multiple VLANs while providing faster convergence times than the traditional STP protocol.

PVST works by creating a separate spanning tree for each VLAN on the network. This allows administrators to customize the spanning tree to the individual needs of each VLAN. Each VLAN has its own root bridge, and the path to it is calculated separately for each VLAN.

Key Features of PVST

• Per-VLAN Optimization Creates individual spanning trees for each VLAN, enabling optimized path selection per VLAN.

• Load Balancing Distributes traffic across different paths by using multiple spanning trees instead of a single one.

• Rapid PVST (RPVST) Enhanced version that uses rapid convergence algorithms for faster topology changes.

• Customizable Configuration Administrators can set root bridge priority for each VLAN and configure path costs per port.

Difference between RSTP and PVST

The following table highlights the major differences between RSTP and PVST:

Conclusion

RSTP provides faster convergence with a single spanning tree for the entire network and is vendor-neutral, while PVST offers per-VLAN optimization and load balancing but is limited to Cisco environments. The choice depends on network requirements, vendor equipment, and the need for VLAN-specific optimization.