What is Network Topology?

Choosing the correct topology for your network is crucial to optimize its functioning. The needs of your organization determine which topology is best suited. Factors like desired performance, cost, and fault tolerance are considered while selecting a network topology.

In this blog, we will explore the different types of network topologies, their advantages, and disadvantages to help you make an informed choice for your network.

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What is Network Topology?

Network topology refers to the layout or structure of a computer network. It defines the way different components in a network, like links, nodes, and connecting devices, are arranged and how they communicate with each other.

The topology of a network determines its performance, cost, reliability, and scalability. It affects factors such as cabling cost, flexibility, fault tolerance, bandwidth, etc. Different network topologies suit different types of networks and organizations.

The five most common types of network topologies are:

• Bus Topology: All nodes connect to a common linear cable called bus.
• Ring Topology: All nodes connect to a circular cable called ring. 
• Mesh Topology: Every node connects to multiple nodes. 
• Star Topology: All nodes connect to a common central hub. 
• Hybrid Topology: Combination of two or more topologies.

We will discuss each one of them in detail.

Types of Network Topology 

Let us now look at different types of network topologies in detail with network topology diagrams.

Bus Topology

In bus network topology, all computers and network devices are connected to a single cable called bus. The bus cable acts as the shared communication medium for all the devices in the network.

When a device wants to transmit data, it sends the data on the bus cable. All other devices receive and check whether they are the intended recipients. The intended recipient accepts the data while others discard it.

Bus topology is inexpensive, easy to implement, and adds devices easily. However, it can be difficult to troubleshoot and isolate faults. Also, if the main bus cable fails, the entire network fails.

Ring Topology 

In ring network topology, all nodes are connected to form a circle. Each node is connected to the next node through a point-to-point link.

Data travels circularly from one node to the next until it reaches the intended recipient. Nodes can transmit data only after receiving a token, a special kind of data packet.

Ring topology provides equal access to the network for all nodes. However, failure of any link can bring down the entire network. Adding or removing nodes also disrupts the network.

Mesh Topology

Every node in a mesh topology is linked to every other node. Point-to-point linkages connect the nodes to one another. Multiple links between nodes in the network can increase redundancy.

Data travels across the network using the shortest path available. If a link fails, the network automatically routes traffic through alternate paths.

Mesh topology is highly fault-tolerant and provides a lot of bandwidth. However, it is difficult and expensive to implement because the number of connections grows exponentially with the number of nodes. 

Star Topology

In a star network topology, all nodes are connected to a central device called a hub through a point-to-point link. The hub acts as a central node that manages and controls the entire network.

All data transmitted between nodes passes through the hub. The hub ensures that the data is directed to the intended recipient.

Star topology is easy to set up and expand, and faults are easily isolated. However, the hub represents a single point of failure. If the hub goes down, the entire network suffers. Star topology also provides limited bandwidth since all data flows through the hub.

Tree Topology 

A tree topology combines the characteristics of bus and star topologies. It consists of groups of star-configured workstations connected to a bus backbone cable.

Tree topology allows the expansion of a star network while still maintaining a bus structure. However, the backbone cable remains a single point of failure. Tree topology can be difficult to configure and wire.

Hybrid Topology

A hybrid network topology combines two or more network topologies to get the benefits of each topology. For example, a star-bus topology consists of stars connected to a bus, while a star-ring topology has stars connected in a ring.

A hybrid topology offers outstanding efficiency, flexibility, and fault tolerance. However, execution and solving issues can be challenging. The implementation of various topologies may also result in increased costs.

Advantages and Disadvantages of Different Network Topologies

The below table explains the advantages and disadvantages of each network topology:

Use Cases of Different Network Topologies

The optimal network topology for an organization depends on its size, budget, and needs. Here are some examples of where different topologies may be suitable:

• Bus topology
  Suitable for small networks where ease of installation and low cost are significant factors. Used in old Ethernet networks.
• Ring topology
  Useful for applications where data integrity and determinism are crucial such as token-based networks. Used in FDDI (Fiber Distributed Data Interface) networks.
• Mesh topology
  Implemented where availability and bandwidth are critical as in air traffic control systems. Used in mobile ad hoc networks (MANETs) and wireless mesh networks.
• Star topology
  Well suited for most modern Ethernet LANs where ease of installation and management are important. Used in most common office networks and Wi-Fi networks.
• Tree topology
  Appropriate where a bus network needs to be expanded while still maintaining a bus structure. Used to some extent in modern Ethernet networks.
• Hybrid topology
  Suitable for large, complex networks where high performance and availability are essential. Used in some wide area networks (WANs) and backbone networks.

Factors Affecting the Choice of Network Topology

There are several factors that determine which network topology is most suitable for an organization:

• Cost
  The cost to implement a network topology depends on factors like the number of connections, length of cables, and networking devices required. Ring, mesh, and hybrid topologies are more expensive than bus and star topologies. 
• Reliability
  The reliability of a network refers to its ability to continue functioning even when a network component fails. Mesh and hybrid topologies provide redundant network connections, so they are more reliable than bus, ring or star topologies where a single point of failure can disrupt the entire network.
• Scalability
  Scalability refers to the ability to expand the network by adding more nodes and components. Mesh, hybrid, and bus topologies are more scalable than ring or star. Adding and removing nodes in a ring or star topology requires reconfiguring the entire topology, which can disrupt the network.
• Bandwidth
  The bandwidth available to each node in a network depends on the topology. Mesh and hybrid topologies provide more bandwidth since multiple network connections are available. Bus, ring, and star topologies offer limited bandwidth since all data flow through a common cable or hub.
• Fault tolerance
  Fault tolerance is the ability of a network to continue functioning even when network components fail or malfunction. Mesh, hybrid, and ring topologies provide fault tolerance through redundant connections. In comparison, bus and star topologies are prone to single points of failure.  

Applications of Different Network Topologies

The type of network topology used depends on the application and use case. Some examples of where different topologies are applied:

• Bus topology
   Bus topology is best suited for small, simple networks with limited nodes. The simplicity and low cost of bus topology make it useful for basic networks where high performance and availability are not major concerns.
  • Simple network for small organizations 
  • Classic Ethernet networks 
  • Low-cost networks where performance is not critical
• Ring topology
  Ring topology is traditionally used in token-based networks such as FDDI (Fiber Distributed Data Interface) networks where determinism and reliability are important. The circular configuration provides redundancy and fault tolerance for specific types of applications.
  • Token Ring networks 
  • FDDI networks 
  • Circular networks with high-reliability requirements
• Mesh topology
  Mesh topology is used in applications where network availability and bandwidth are crucial such as real-time mobile ad hoc networks and high-performance computing. The mesh configuration with multiple redundant connections provides fault tolerance and increased performance.
  • Mobile ad hoc networks (MANETs)
  • High performance computing clusters
  • Wireless mesh networks
  • Networks where availability and high bandwidth are critical
• Star topology
  Star topology is popular for small to mid-size organizations because it is simple to set up, cost-effective and meets basic connectivity needs. Variations of star topology are used in most common wired and wireless networks including Ethernet and Wi-Fi networks.
  • Most common modern Ethernet networks 
  • Wireless networks (Wi-Fi) 
  • Simple networks with limited nodes
• Tree topology
  Tree topology is used to some extent in modern Ethernet networks to expand star topologies while retaining a basic bus configuration. It provides more fault tolerance than a star while being simpler than a mesh topology.
  • Expansion of Ethernet-based star topologies 
  • Networks that require a simple bus structure with some fault tolerance
• Hybrid topology
  Hybrid topology is suitable for demanding enterprise networks where a combination of multiple topologies is needed to meet goals for performance, availability, reliability and cost. The mix of topologies provides flexibility, scalability and redundancy for mission-critical networking.
  • Backbone networks requiring very high availability  
  • Complex networks where flexibility and performance are essential 
  • Large enterprise networks

Conclusion

The network topology significantly impacts a network’s performance, reliability, and scalability. Choosing the right topology for your organization is crucial based on factors like cost, security, available bandwidth, and technology.

While bus and star topologies are simple to set up and suitable for small networks, ring, and mesh topologies provide more redundancy. Hybrid topologies give the flexibility to leverage the benefits of multiple topologies. Ultimately, the needs and budget of your organization will determine which topology fits best.