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What is Network Topology - 5 Most Important Network Topologies

There are many ways in which computers can be connected together in a computer network. The way in which computers or other devices are connected in a network is called Network Topology. It represents the shape of network.

The 5 most important and commonly used network topologies are as follows:
  1. Bus topology
  2. Star topology
  3. Ring topology
  4. Tree topology
  5. Mesh topology
    1- Bus Topology
        In Bus topology, all nodes (or devices) are connected to a common communication medium. Usually, a central cable is used as communication medium. This cable is called Bus. The computers or nodes are connected to the Bus through interface connector. The ends of bus (central cable) are closed with terminators. These terminators are used to absorb signals.

    Working of Bus Topology
    In bus network, each computer is assigned a unique address. When a computer sends a message to another computer, it also attaches the address of the destination computer with message. This message moves from one computer to other through the bus. Each computer connected to the network checks the message. If the address (attached with message) matches with the address of computer, then it accepts the message. Otherwise, the message moves to the next computer. In this way, the message is received by the destination computer.
    Advantages
    • It is very simple and easy to install.
    • It requires small length of cable to connect computers.
    • It is less expensive.
    • When a node is added and removed to and from the network, the network is not affected.
    • If one node fails, other nodes are  not affected.
    Disadvantages
    • It can support only a small number of nodes or computers. As the number of computers increases, the network get slower.
    • Entire network fails if there is any problem in the central cable.
    2- Star Topology
        In a star network, all computers or nodes are directly connected to a central device. The central device is called Hub. Typically, the nodes are connected to the Hub with unshielded twisted pair (UTP). Star topology is most commonly used in LAN. This form of network shape looks like a Star.

    Working of Star Topology
    In Star topology, the computers communicate with each other through central Hub. The sending computer sends data to the Hub. The Hub sends data to the receiving computer. In this way, data is transferred from one computer to another.

    Advantages
    • It is easy to install and to maintain.
    • New nodes can easily be added and removed to and from the central Hub without affecting the network.
    • If any node or cable fails, other nodes are not affected.
    Disadvantages
    • It requires more cable than any other topologies. So it becomes more costly.
    • This type of network depends upon the central Hub. If Hub fails, the entire network breaks down.
    3- Ring Topology
    In ring topology, each computer is connected to the next computer and the last computer is connected to the first. Thus, a ring of computers is formed.

    Working of Ring Topology
    When a computer sends a message to another computer on the network, the message flows from one computer to the next computer. Every computer receives message from previous computer and transmits it to the next computer until the destination computer receives the message. Token passing method is used in this topology.

    Advantages
    • It is less expensive than star topology.
    • It is easy to install and to maintain.
    • All computers have equal access to the network.

    Disadvantages
    • If one node fails, it affects the entire network.
    • Adding or removing a computer in the network affects the whole network.
    4- Tree Topology
        Tree topology has combined features of bus and star topology. Typically to form a tree network, multiple star topologies are combined together through central cable or bus. The tree network looks like a tree structure.

    Working of Tree Topology
    In tree topology network, one central hub and multiple secondary hubs are used. The central hub is an active hub. It contains a repeater (a hardware device), which regenerates the received signals of data. The secondary hubs usually are passive hubs. Each passive hub controls the nodes directly connected to it. It also exchanges data to other devices connected to the other secondary hubs (or same hub) through the central hub. The secondary hub may also act as active hub if another secondary hub is directly connected to it. The cable TV network is an example of tree topology. In this network, main cable is divided into branches and each branch is further divided into smaller branches and so on. The hub is used when a new branch is created.

    Advantages
    The tree topology has the same advantages as star topology but it has some additional advantages. The main advantage is:
    • It allows more devices to be connected to the central Hub.
    Disadvantages
    The tree topology also has the same disadvantages as star topology but it has some additional disadvantages. The main disadvantage is:
    • It is more expensive because more hubs are required to be installed in the network.
    5- Mesh Topology
        In mesh topology, each node is directly connected to every other node on the network. This type of network involves the concept of routes. Mesh topology is rarely used in LAN. Some WANs like the Internet use mesh topology.

    Working of Mesh Topology
    In mesh topology, each node can send message to the destination through multiple paths. It means that each node of mesh network has several possible paths to send or to receive message.

    Advantages
    • It has multiple links, so if one route is blocked then other routes can be used for data communication.
    • It ensures the data privacy or security, because every message travels along a dedicated link.
    • Troubleshooting of this topology is easy as compared with other networks.
    • It performance is not affected with heavy load of data transmission.
    Disadvantages
    • It becomes very expensive because a large number of cabling and I/O ports are required.
    • It is difficult to install.

    5 Responses to “What is Network Topology - 5 Most Important Network Topologies”

    mahasiswa teladan said...
    9 September 2013 at 01:19

    hi..Im student from Informatics engineering, this article is very informative, thanks for sharing :)


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    Yohancy Nova said...
    18 April 2014 at 19:29

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