Close Menu

    Subscribe to Updates

    Get the latest creative news from FooBar about art, design and business.

    What's Hot

    Windows 10 End of Service: What Must Be Done

    19 March 2025

    Elementor #7217

    5 March 2025

    Why Windows is Still the Best for Gamers: A Deep Dive

    27 February 2025
    Facebook X (Twitter) Instagram
    Facebook X (Twitter) Instagram Vimeo
    Let's Tech It Easy
    Subscribe Login
    • Homepage
    • About
    • Blog
      • Computers
      • Cloud
      • Gaming
      • Cyber Security
      • iPhone
      • Mac
      • Windows
      • Android
    • Contact
    • My Tickets
    • Submit Ticket
    Let's Tech It Easy
    Home»Computers»Spanning Tree Protocol (STP)
    Computers

    Spanning Tree Protocol (STP)

    Diyana WeerasuriyaBy Diyana Weerasuriya10 January 2023Updated:27 January 2023No Comments6 Mins Read
    Facebook Twitter Pinterest LinkedIn Tumblr WhatsApp VKontakte Email
    Share
    Facebook Twitter LinkedIn Pinterest Email

    What is spanning Tree Protocol (STP)?

    The companies and organisations are connected through networking. There should be a proper networking architecture for redundancy. Redundancy means providing multiple paths to keep the flow of data without traffic. All switches use Spanning Tree Protocol. 

    Spanning Tree Protocol is a layer two protocol used to prevent loops created when exchanging data on Local Area Networks (LAN), which contain redundant paths. This technique ensures that there is only one logical path between all the destinations on the network by blocking the redundant paths that might cause a loop. This also allows the inclusion of backup links by fault tolerance.

    Spanning trees choose the optimum paths using an algorithm to look for redundant LAN links. It is primarily used to switch all links to forwarding or blocking modes. Following this procedure, it’s likely that all links without redundant links will be in the forwarding state. Links that were redundant but less effective than those chosen will be blocked. With Spanning Tree, there is no load-sharing feature.

    How does this work?

    Before designing the STP, the network topology should be planned and completed. For this configuration, the STP should be enabled with the same STP version for all the switches in the LAN.

    What is a Root bridge?

    The root bridge is the coordinate point for all the switches in a Spanning Tree topology. A selection procedure occurs when every controller is linked, choosing the bridge with the lowest bridge ID as the root bridge.

    What is a root port?

    A single port with the lowest travel cost to the root bridge is known as the root port. For root users, access is limited to ports from 1 to 1023. Therefore, we must assign those ports with root access. The range of ports utilised for user server applications is 1024 to 49151.

    What is a designated port?

    The port that can have the lowest path cost on LAN which is used to reach the root bridge.

    Figure 1: https://www.orbit-computer-solutions.com/spanning-tree-protocol-stp/

    The Spanning Tree Protocols can identify the links in the network and shut down the redundant networks, preventing loops. A root bridge is selected when the networks exchange the BPDU (Bridge Protocol Data Unit) messages. According to the root bridge chosen, every switch determines the port to which it will communicate with the root port.

    BDPU message – a data message transmitted through LANs to detect the loops in the network topologies.

    If more than one link gets connected to the root bridge, then a forwarding port(a designated port) is elected while the others are blocked.

    1. The MAC Address and the Priority value should select a root bridge. The switch with the lowest MAC address is chosen as the root bridge.
    2. Then the root port is selected.
    3. Then each switch needs to identify a single root port close to the routing bridge. This should be in the forwarding state. 
    4. If two different switches belong to the same segment, they must be blocked to avoid loops. The switch with the higher MAC Address value and its designated port needs to be stopped.

    Figure 2: https://www.pluralsight.com/blog/it-ops/switching-and-stp

    Port states of STP

    There are five port states, but they are switched only to one of the ports to control frame forwarding.

    1. Disabled – does not allow any frame forwarding or STP operations. The network administrator manually disables the switch port.
    2. Blocking does not allow frame forwarding and discards the frames received from the network. But the network listens and processes the BPDU messages.
    3. Listening – Moves from the blocking state; the port rejects the frames attached to the network segment. This receives the BPDU messages and redirects them to the switch for processing.
    4. Learning – The listening state port is changed to the learning state. It listens to the processed BPDUs and rejects the frames from the attached network segments. Then it updates the address table.
    5. Forwarding – the learning state transits to the forwarding state and starts forwarding frames throughout the network segments. It consists of the structures attached to the network segment and those delivered from another port. The port receives and processes the BPDU messages and updates the table.

    Figure 3: https://community.cisco.com/t5/networking-blogs/spanning-tree-protocol-from-a-feature-ccna-s-perspective-by/ba-p/3101592

    Modes of STP

    STP is based on algorithm new modes were created with the recent introduction of the convergence behaviours and the bridge port roles by the IEEE. Rapid STP, Multiple STP, Per-VLAN STP, and Rapid Per-VLAN STP(rapid PVST) are commonly used Spanning Tree Protocols. 

    The network should enter the required mode to enable an STP on a bridge or switch.

    Spanning-tree mode <protocol mode> 

    e.g., Spanning-tree mode rstp

    enables the Real Time Streaming Protocol on the switch. 

    Advantages of using STP

    • It helps in link redundancy by preventing unwanted loops.
    • Support the bridges and the switches
    • The algorithms of STP ensure clarity in building a root bridge that has traffics and ensures the efficiency of data forwarding.
    • Easy to design and maintain
    • This allows the information to flow safely between the devices by avoiding the loops.
    • It creates a pathway to limit the number of open paths and arrange them accordingly.
    • It provides backups when the connection gets into any technical issue.
    • If one path is not functioning correctly, the STP closes that path and opens another way. 
    • It works with 802.1D 1998 bridges. 
    • The CPU and memory requirements are less required. 

    Disadvantages of using STP

    • You are limited to a single instance on any physical interface.
    • STP is slower than RSTP because STP is timer based.
    • It is not recommended for multiple VLANs because it limits the number of forwarding paths.
    • If the topology changes, it does not provide a fast network confluence.
    • Edge ports are not suitable when IEEE 802.1D STP is configured.
    • Total network capacity may not be identified when using STP.

    Alternatives to STP

    The main two options are;

    • Transparent Interconnection of Lots of Links(TRILL)
    • Shortest Path Bridging (SPB)

    TRILL uses layer three network routing techniques which create clouds and link them to internet protocol nodes as single IP subnets

    SPB combines with MPLS(Multiprotocol Label Switching) and is backward compatible with STP.

    data Networking TECHNOLOGY xtech
    Share. Facebook Twitter Pinterest LinkedIn Tumblr WhatsApp Email
    Previous ArticleFree-space laser communication
    Next Article Neuromorphic Computing
    Diyana Weerasuriya

    Related Posts

    Windows 10 End of Service: What Must Be Done

    19 March 2025

    Elementor #7217

    5 March 2025

    Why Windows is Still the Best for Gamers: A Deep Dive

    27 February 2025

    Accessing a Windows External Hard Drive on Mac

    26 February 2025
    Leave A Reply Cancel Reply

    This site uses Akismet to reduce spam. Learn how your comment data is processed.

    Demo
    Our Picks
    • Facebook
    • Twitter
    • Pinterest
    • Instagram
    • YouTube
    • Vimeo
    Don't Miss
    Business

    Windows 10 End of Service: What Must Be Done

    By Uneeb19 March 20250

    On October 14, 2025, Microsoft will officially end support for Windows 10, signalling a major shift…

    Elementor #7217

    5 March 2025

    Why Windows is Still the Best for Gamers: A Deep Dive

    27 February 2025

    Accessing a Windows External Hard Drive on Mac

    26 February 2025

    Subscribe to Updates

    Get the latest creative news from SmartMag about art & design.

    You too can join us

    If you also think about technology and want to contribute either as a mentor or even from a learner’s perspective, look no further and join us. Write us at [email protected] and share your opinion. Our team will get back by sending you an invite to join the platform as a contributor. Empower others, empower yourself so each one of us can play with the technology safely one day without being scared.

    Subscribe Here
    Loading
    For Partnership Worldwide

    Contact:

    [email protected]

     

    About Us
    About Us

    “Let’s Tech It Easy” or popularly known as “LTIE” is the blogging platform for everyone who wants to share and learn about technology. It is an initiative by the serial techpreneur Vish when he realized the wide gap between the pace at which the technology is evolving and at which it is getting adopted by a wider audience.

    Email Us: [email protected]

    Latest Posts

    Upgrading RAM

    10 March 2023

    Desktop Vs Laptop

    10 March 2023

    Data Recovery

    3 March 2023

    MacOS on Windows Virtual Box

    10 February 2023

    macOS Monterey and what’s new in it?

    12 April 2022
    New Comments
    • How to Troubleshoot Sound and Mic on Windows 10 - Let's Tech It Easy on How to Access Troubleshooters on Windows 10
    • How to Stay Safe While Using Public Wi-Fi Networks - Let's Tech It Easy on Internet Security for Home Users – VPN 101
    • How to Set up Oracle VirtualBox on a Mac - Let's Tech It Easy on How to Install Windows 10 on a Mac Using Boot Camp Assistant
    • DoS Attack Implementation and Prevention in Ubuntu – Let's Tech It Easy on Top Kali Linux Commands
    Facebook X (Twitter) Instagram Pinterest
    • Homepage
    • About
    • Blog
    • Contact
    • Computers
    • Cloud
    • Gaming
    • Cyber Security
    • iPhone
    • Mac
    • Windows
    • My Tickets
    • Submit Ticket
    © 2025 LetsTechitEasy. Designed by Sukrit Infotech.

    Type above and press Enter to search. Press Esc to cancel.

    Sign In or Register

    Welcome Back!

    Login below or Register Now.

    Lost password?

    Register Now!

    Already registered? Login.

    A password will be e-mailed to you.