Difference between STP and RSTP

Spanning Tree Protocol (STP) and Rapid Spanning Tree Protocol (RSTP) are the network protocols that are used to prevent loops from forming in the topologies of networks with redundant links. The speed of convergence is the primary difference between the STP and RSTP network protocols.

STP takes a while to converge; on the other hand, RSTP converges significantly more quickly. In addition, RSTP provides fresh ideas, which include point-to-point connectivity and edge ports that speed the convergence process. RSTP network protocols offer faster convergence than STP protocols, and it is a more effective method of preventing loops in networks with duplicate links.

Read this article to find out more about STP and RSTP and how they are different from each other.

What is Spanning Tree Protocol?

A redundant link network topology uses the Spanning Tree Protocol (STP), which is a network protocol that is used to avoid loops. In order to prevent loops from forming in the network, it is used to make sure that there is only one active path between two network devices.

In order for STP to function, one of the many accessible paths is chosen as the "root path," and any further redundant links are then turned off. The root path is chosen based on a number of factors, which include the root's shortest path, lowest path cost, and lowest bridge ID. Then, the STP algorithm decides which links may be activated securely and which ones need to be disabled.

Spanning Tree Protocol supports the five port states: forwarding, learning, listening, blocking, and disabled. It contains the two bits from the flag octet.

STP has some disadvantages such as a slow convergence time and an inability to adjust to quick changes in the network topology. In order to overcome these restrictions, the Rapid Spanning Tree Protocol (RSTP) was created.

What is Rapid Spanning Tree Protocol?

A network protocol called Rapid Spanning Tree Protocol (RSTP) is used to prevent loops in topologies when redundant links are used. In the event of a network change, it is meant to provide faster convergence as an evolution of the Spanning Tree Protocol (STP).

Edge ports and point-to-point communications are two new ideas that RSTP introduces that significantly speed up convergence. In the spanning tree calculation, edge ports are ports that connect to a single device only. Links between two devices that don't require the use of a specific port are called "point- to-point" links.

The Rapid Spanning Tree Protocol supports the three port states, i.e., forwarding, learning, and discarding. It also contains flag bits such as Bit 0 for TCN, bit 1 for proposal, Port role bits 2 and 3, learning bit 4, 5, forwarding bit 6, and TCN bit 7.

In general, Rapid Spanning Tree Protocol offers quicker and more effective convergence than Spanning Tree Protocol, which makes it a better option for networks that need to react quickly to changes in the network topology.

Difference between STP and RSTP

The following table highlights the major differences between Spanning Tree Protocol and Rapid Spanning Tree Protocol −

Characteristics	STP	RSTP
Standard	802.1D IEEE standard	802.1W IEEE standard
Types of Links	STP doesn’t have any link types	RSTP has two link types. They are shared links and point-to-point link
Network Convergence	In response, STP provides slower network convergence	In response, RSTP provides faster network convergence
Post States	STP contains the five port states	RSTP contains the three port states
Port Roles	STP contains the 3 port roles	RSTP contains the 4 port roles, and an alternative port
Stands for	STP stands for Spanning Tree Protocol	RSTP stands for Rapid Spanning Tree Protocol
Port Functions	Spanning Tree Protocols contain the three port functions. They are − Root Port Designated Port Blocked Port	The Rapid Spanning Tree Protocol contains the four port functions. They are − Root Port Designated Port Blocked Port Alternate Port

Conclusion

The ability to prevent loops in network topologies with redundant links is what differentiates the Spanning Tree Protocol (STP) and Rapid Spanning Tree Protocol (RSTP). The traditional protocol STP, which was created to stop loops, has significant drawbacks, such as a lengthy convergence time and the inability to adjust to quick changes in network topology.

As a development of STP, RSTP was created to alleviate these drawbacks and offer quicker convergence. With the use of new concepts like edge ports, point-to-point links, new port roles, and BPDUs, RSTP significantly increases convergence's efficiency and speed.

The decision between STP and RSTP will ultimately come down to the particular needs of the network, with RSTP being a better option for networks that need to react quickly to changes in network topology.