Spanning Tree improves the performance of Ethernet LAN traffic by eliminating loops and rerouting around malfunctioning nodes.
The Spanning Tree Protocol, also known as “Spacing Tree,” is the equivalent of Waze or MapQuest for modern Ethernet networks. It directs traffic along the most efficient route based on current conditions.
Based on an algorithm developed by American computer scientist Radia Perlman for Digital Equipment Corporation (DEC) in 1985, Spanning Tree was developed. Its primary objective is to prevent redundant links and communication routes in complicated network architectures from looping. As a supplementary function, Spanning Tree can route packets around problematic locations to ensure communication over networks that may be experiencing issues.
Spanning Tree topology vs. Ring topology
In the 1980s, when businesses first began connecting their computers, the ring network was one of the most prevalent methods. In 1985, IBM’s Token Ring technology was first implemented.
Each node in a ring network topology is connected to two others: one in front of it on the ring and one in back. Signals can only travel in one direction around the ring, and packets are forwarded at each node along the way.
Simple ring networks function well when there are few computers in a network. However, the rings do not function as well when there are hundreds or thousands of machines in a network. In order to communicate information with a machine in the adjacent room, a computer may have to transfer packets over hundreds of nodes. Bandwidth and throughput are particularly problematic when just one direction of traffic is allowed and there is no backup plan in case a node along the route fails or becomes overloaded.
In the 1990s, as Ethernet became faster (100Mbit/sec was released in 1995) and the cost of an Ethernet network (bridges, switches, and cables) became significantly less than that of Token Ring, Spanning Tree won the LAN topology wars and Token Ring quickly died out.
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How Does Spanning Tree Protocol Works?
Spanning Tree is a protocol for transmitting data packets to their destination. It is akin to being both a traffic cop and a civil engineer for the data highways. Layer 2 is the data link layer, hence it is simply concerned with delivering packets to their destination. It does not care what type of packets are sent or what data is contained within them.
Spanning Tree is now so prevalent that it is written into the IEEE 802.1D networking standard. According to the standard, there can be only one active path between any two endpoints or stations in order for them to function.
Spanning Tree is designed to prevent data flowing between various areas of a network from becoming looped. In general, loops wreak havoc on the built-in forwarding algorithm of network devices. This indicates that the gadget is unaware of where to send data packets. This can result in duplicate frames or duplicate packets being transmitted to several destinations. Messages can be sent repeatedly. The recipient of a communication can retrieve it. A network can potentially crash if there are too many loops. This is because loops use bandwidth without providing significant benefits and prevent other data from passing.
The Spanning Tree Protocol closes all but one path for each data packet, preventing the formation of loops. Switches in a network employ Spanning Tree to construct root pathways and bridges over which data can travel, as well as to cut off duplicate paths, rendering them inactive and unusable while a major path is open.
No matter how large or complex a network becomes, network communications flow smoothly due to this fact. Spanning Tree employs software to create single paths for data to move through a network. This is comparable to how network engineers created single paths through the old loop networks using hardware.
Benefits of Spanning Tree Protocol (STP)
The primary purpose of Spanning Tree is to prevent routing loops from occurring in a network. But there are other positive aspects to it.
Spanning Tree is able to determine if a node on one of the principal paths has been disabled because it constantly searches for and defines which network paths can be utilised to transmit data packets. This can occur for a variety of reasons, including faulty hardware or a change in network configuration. It could even be a temporary issue caused by bandwidth or another factor.
When Spanning Tree determines that a principal path is no longer in use, it can rapidly open a previously closed path. It can then transfer data around the problem, making the detour the new principal path or sending packets back to the original bridge if it becomes accessible again.
The original Spanning Tree established these new connections fast, but in 2001, the IEEE introduced the Rapid Spanning Tree Protocol (RSTP). RSTP, also known as the 802.1w version of the protocol, was created to accelerate recovery from network changes, temporary outages, and component failure.
And while RSTP offered new mechanisms for pathways to converge and new functions for bridge ports to accelerate the process, it was also designed to be compatible with the original Spanning Tree. So that devices with either version of the protocol can operate on the same network.
Drawbacks of Spanning Tree Protocol
Even though Spanning Tree has been around for a long time and is utilised by nearly everyone, there are some who believe the time has come to retire it. The greatest issue with Spanning Tree is that it cuts off potential channels for data to travel through a network, which might result in loops. About 40 percent of the viable network paths in every network using Spanning Tree are blocked.
In extremely complex networking systems, such as those found in data centres, the capacity to scale up fast to meet demand is vital. If Spanning Tree did not have so many limitations, data centres might increase bandwidth without purchasing additional networking hardware. It’s amusing that this is occurring because Spanning Tree was designed for circumstances such as these. And now, the protocol’s anti-looping safeguard is preventing these environments from being as good as they could be.
Several-Instance Spanning Tree (MSTP) is an improved version of the protocol that enables the usage of virtual LANs and the simultaneous opening of multiple network channels without the formation of loops. Even when MSTP is implemented, there are still a large number of data channels that cannot be utilised on a network.
There have been numerous non-standardized attempts throughout the years to increase the bandwidth restrictions of Spanning Tree. Even if their creators claim that some of them work, the most of them are not entirely compatible with the core protocol. This necessitates that organisations either implement the non-standard adjustments on all of their devices or find a way to make them compatible with standard Spanning Tree switches. It is typically not cost-effective to maintain and support various versions of Spanning Tree.
