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

Last Updated : 17 Mar, 2023
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1. 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 clog up the network, broadcast storm, etc. eventually it can even lead to failure of the switches.

Advantages of STP:

  • It is a mature protocol that has been widely used in networks for many years.
  • It can handle complex topologies and prevent network loops by blocking redundant links.
  • It provides a stable network topology by ensuring that only one path is active at any given time.
  • It is supported by most network devices and can be configured easily.
  • It does not require special hardware or software.

Disadvantages of STP:

  • It has slow convergence time, which can cause network downtime and performance issues.
  • It can lead to inefficient use of network resources by blocking links even when they are not actually causing a network loop.
  • It cannot detect changes in the network topology quickly and may cause network instability.
  • It may require manual configuration and management in large networks.

2. Rapid Spanning Tree Protocol (RSTP) :  
Rapid spanning tree protocol(RDTP) is an enhanced version of the Spanning Tree Protocol. The IEEE standard of RSTP is 802.1w. There are many similarities between STP and RSTP, RSTP is backward-compatible with STP. It averts network loops by blocking unnecessary ports.

Advantages of RSTP:

  • It has faster convergence time than STP, which reduces network downtime and improves performance.
  • It can detect changes in the network topology quickly and reconfigure the network accordingly.
  • It can use link aggregation to provide faster network throughput and redundancy.
  • It supports VLANs and provides faster convergence time for VLANs.

Disadvantages of RSTP:

  • It may require newer network hardware or software to support the protocol.
  • It may require more processing power and memory than STP.
  • It may be more complex to configure and manage than STP.

Similarities between the two protocols:

  • Both protocols prevent network loops by blocking redundant links in the network.
  • Both protocols use a root bridge to determine the active path in the network.
  • Both protocols use a metric to determine the best path to the root bridge.
  • Both protocols use BPDU (Bridge Protocol Data Unit) messages to exchange information with other network devices.
  • Both protocols support the use of VLANs to segment the network.
  • Both protocols ensure that there is only one active path in the network to prevent broadcast storms and other network issues.

Difference between STP and 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.

In conclusion, both STP and RSTP are network protocols used to prevent loops and ensure network redundancy in Ethernet networks. However, RSTP is an improved version of STP that provides faster convergence time, enhanced network stability, and reduced downtime. RSTP is a more efficient protocol that is preferred over STP for high-performance networks. If you are designing a new network, it is recommended that you use RSTP instead of STP to ensure faster convergence and better network performance.

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