Difference between Spanning Tree Protocol (STP) and Rapid Spanning Tree Protocol (RSTP) (original) (raw)

Last Updated : 23 Jul, 2025

Spanning Tree Protocol (STP) and Rapid Spanning Tree Protocol (RSTP) are used in Ethernet networks to stop loops from forming. They help create a stable, loop-free network and prevent problems like broadcast storms. Both are meant to make networks more reliable, but they differ in how fast they work, how they function, and how flexible they are in the use.

**Spanning Tree Protocol (STP)

STP is also known as spanning tree protocol is a layer 2 (Data link layer) protocol, it runs on switches and bridges. The IEEE standard of STP is 802.1D. STP is a feature used to prevent loops when using redundant switches. For example, we have three switches they are all linked together and without STP a loop could form causing several problems like it can blocked the network, broadcast storm, etc. eventually it can even lead to failure of the switches.

**Advantages of STP

**Proven and Reliable: STP is a well-established protocol that has been used in networks for many years.
**Prevents Network Loops : It helps manage complex network structures and stops loops by blocking extra or redundant paths.
**Maintains Network Stability : STP ensures a stable network by allowing only one active path between devices at any given time.
**Widely Supported : Most network devices support STP, and it can be configured with minimal effort.
**No Special Requirements : STP works without needing any special hardware or software.

**Disadvantages of STP

**Slow Convergence: One of the main drawbacks of STP is its slow convergence time. When there is a change in the network, STP takes a while to adjust, which can lead to temporary network downtime and performance issues.
**Inefficient Use of Links: STP can be inefficient because it blocks links even if they aren’t actually causing a loop. This means some network paths go unused, which reduces overall network efficiency.
**Delayed Topology Updates: STP is slow to detect and respond to changes in the network topology. As a result, it may cause delays in re-establishing connections and lead to network instability.
**Manual Configuration: In large or complex networks, STP often requires manual configuration and ongoing management, which can increase the workload for network administrators.

**Rapid Spanning Tree Protocol (RSTP)

Rapid Spanning Tree Protocol (RSTP) is an improved version of the original Spanning Tree Protocol (STP). It is defined by the IEEE standard **802.1w. RSTP shares many features with STP and is also backward compatible, meaning it can work with devices that still use STP. Like STP, RSTP prevents network loops by blocking unnecessary ports, but it does so much faster and more efficiently.

**Advantages of RSTP

**Faster Convergence: RSTP has a much quicker convergence time compared to STP. This reduces network downtime and improves overall performance.
**Quick Topology Changes: It can detect changes in the network quickly and reconfigure the paths automatically.
**Link Aggregation Support: RSTP can use link aggregation, which helps boost network speed and provides redundancy.
**Better VLAN Support: RSTP offers faster convergence times even in networks using VLANs.

**Disadvantages of RSTP

**Hardware and Software Requirements: Some older network devices may not support RSTP and might require updates or replacements.
**Higher Resource Usage: RSTP may need more processing power and memory compared to STP.
**More Complex Management: It can be slightly more complex to configure and manage than STP, especially in large networks.

**Similarities between STP and RSTP

There are many similarities between the STP and RSTP protocols as discussed below :

**Loop Prevention: Both STP and RSTP are designed to prevent network loops by blocking redundant links in the network.
**Root Bridge Selection: They both rely on a root bridge to determine the best active path through the network.
**Path Selection Metric: STP and RSTP use a metric (called path cost) to decide the most efficient route to the root bridge.
**BPDU Communication: Both protocols use BPDU (Bridge Protocol Data Unit) messages to exchange network topology information with other switches.
**VLAN Support: STP and RSTP both support the use of VLANs, allowing for network segmentation and better traffic management.
**Single Active Path: Each ensures that only one active path exists between devices at any given time, helping to prevent broadcast storms and other network issues.

**Difference between STP and RSTP

**STP	**RSTP
Its IEEE standard is 802.1D.	Its IEEE standard is 802.1W.
In STP only the root bridge sends BPDU (Bridge protocol data unit) and it is transferred by others.	In RSTP all bridges can forward BPDUs.
STP has three port roles (i.e., Root Port, Designated Port, Blocked Port).	RSTP has four-port roles (i.e., Root Port, Designated Port, Alternate Port, Backup Port).
STP has five port states (i.e., Forwarding, Learning, Listening, Blocking, Disabled).	RSTP has three port states (i.e., Forwarding, Learning, Discarding).
It doesn’t have any link type.	It has Two link types i.e., Shared link and Point to point link.
STP provides slower network convergence in response.	RSTP provides significantly faster network convergence.
Flag bits used in STP are Bit 0 for TCN (Topology Change Notification) and Bit 7 for TCA (Topology Change Acknowledgement).	Flag bits used in RSTP are Bit 0 for TCN, Bit 1 for Proposal, Bit 2 and 3 for Port role, Bit 4 for Learning, Bit 5 for forwarding, Bit 6 for Agreement, and Bit 7 for TCN.