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Network Topology

Network topology refers to the physical or logical layout of a computer network. It describes how computers, cables, switches, and other devices are arranged and connected to each other.

A network topology is the arrangement of devices (nodes) and connections (links) in a computer network. It shows how computers, servers, and other devices are connected and how data flows between them.

There are two main types of topology:

  1. Physical Topology: The actual physical layout of cables and devices.
  2. Logical Topology: How data moves across the network, regardless of physical layout.

Types of Network Topology

Network topology describes how computers and devices are arranged in a network. Below are various network topologies that include:

1. Bus Topology

Bus topology is a network layout where all computers are connected to a single central cable, called the bus or backbone. It is bi-directional. It is a multi-point connection and a non-robust topology because if the backbone fails the topology crashes. In Bus Topology, various MAC (Media Access Control) protocols are followed by LAN ethernet connections like TDMA, Pure Aloha, CDMA, Slotted Aloha, etc.

Note:

  • Coaxial or twisted pair cables are mainly used in bus-based networks that support up to 10 Mbps.
  • NA common example of bus topology is the Ethernet LAN, where all devices are connected to a single coaxial cable or twisted pair cable. This topology is also used in cable television networks.

Advantages
  • Easy to install: The layout is simple; devices connect to a single cable.
  • Low cost: Requires less cabling compared to other topologies.
  • Good for small networks: Works well when only a few devices are connected.
  • Less cable required: Saves installation cost and time.
  • Simple to expand: New devices can be added by joining them to the main cable.
Disadvantages
  • Main cable failure - network failure: Entire network stops working if the bus (main cable) breaks.
  • Slow performance: Data collisions occur when many devices transmit at once.
  • Difficult to troubleshoot: Finding a fault in the long cable is hard.
  • Not scalable: Adding too many devices decreases performance.
  • Limited cable length: Signal strength weakens after a certain distance (attenuation).
Where to used?
  • Small LANs
  • Early Ethernet networks
  • Temporary networks

2. Star Topology

Star topology is a network layout in which all devices are connected to a central device, such as a hub. The central device acts as a controller for all communication.

  • Each device has its own separate cable connecting to the hub or switch.
  • Data from any device first travels to the central device, which then forwards it to the destination device.
  • The central hub/switch manages traffic.

Advantages
  • Easy to install and manage: Simple structure with a central device.
  • Failure of one device does NOT affect the entire network: Each device is independently connected.
  • Easy to add or remove devices: Good for growing networks.
  • High performance: Switches reduce collisions and increase efficiency.
  • Easy troubleshooting: Faults are easier to locate because each device has a separate connection.
Disadvantages
  • Central device failure shuts down the entire network: Hub/switch is a single point of failure.
  • More cabling required: Each device needs its own cable.
  • Higher cost: Requires a hub or switch, plus extra cables.
  • Performance depends on the central device: A slow hub = slow network.
Where to used?
  • Home networks
  • Schools and colleges
  • Office LANs
  • Modern Ethernet networks

3. Tree Topology

Tree topology is a network layout that combines characteristics of Star and Bus topologies. It has a root node (main hub/switch) connected to multiple subordinate nodes, which may have their own branches. It arrange a network like a tree with a root, branches, and sub-branches. It is a hierarchical network structure that connects multiple star networks to a central hub. It is scalable and organized but depends heavily on the root hub.

  • The root device connects to other hubs/switches.
  • Each lower-level hub connects to multiple devices.
  • Data moves from leaves (PCs) → through branch hubs → to root hub (and vice versa).


Advantages
  • Highly scalable: Ideal for large networks (schools, offices, corporates).
  • Easy to manage and troubleshoot: Fault in one branch does not affect other branches.
  • Supports future expansion: You can add more branches at any level.
  • Hierarchical structure: Clear and organized layout for administration.
Disadvantages
  • Expensive: Requires many cables, hubs, and switches.
  • Root node failure affects the entire network: If the main hub goes down, all branches stop working.
  • Complex installation: Difficult to set up compared to bus or star topology.
  • Maintenance becomes challenging: More devices = more points of failure.
Where to used?
  • Universities
  • Corporate offices
  • Large organizations
  • WAN and complex LAN setups

4. Ring Topology

Ring topology is a network layout in which each device is connected to exactly two other devices, forming a circular path.

  • Data moves from one device to the next in a circular path.
  • Each device receives the data and passes it to the next evice.
  • A special signal called a token is used in some ring networks (Token Ring).
Ring topology connects devices in a closed loop where data moves in one direction. It offers equal access and stable performance but fails if any device or cable breaks.

Advantages
  • Faster than bus topology: Because data travels in one direction without collisions.
  • Equal access to devices: No device dominates the network.
  • Performance remains good even with many devices: No congestion like bus topology.
  • Easy to identify cable faults: Some ring networks have fault detection.
Disadvantages
  • If one device/cable fails, the whole network may fail: The ring breaks and data cannot circulate.
  • Difficult to troubleshoot: Finding the faulty node takes time.
  • Slow if many devices pass data token-by-token: Each device must wait for its turn.
  • Adding or removing devices disrupts the network: Network must be temporarily shut down.
Where to used?
  • Older LAN technologies (Token Ring)
  • Some office networks
  • Fiber Distributed Data Interface (FDDI) system

5. Mesh Topology

In a mesh topology, every device is connected to another device via a particular channel. Every device is connected to another via dedicated channels. These channels are known as links. In Mesh Topology, the protocols used are AHCP (Ad Hoc Configuration Protocols), DHCP (Dynamic Host Configuration Protocol), etc.


Types of Mesh Topology
  • Full Mesh: Each node connects to every other node.
  • Partial Mesh: Some devices are fully connected; others are connected only to a few.
Advantages
  • High reliability: If one link fails, data can use another route.
  • No network downtime: Failure of one device does NOT affect the entire network.
  • High security: No single point of failure; direct connections prevent data interception.
  • Fast communication: Direct links make data transfer quicker.
  • Scalable for critical systems: Best for high-availability environments (military, banking).
Disadvantages
  • Very expensive: Requires a lot of cables and hardware.
  • Complex installation: Hard to set up and maintain.
  • Difficult troubleshooting: Many connections → more complexity.
  • Not practical for small or normal networks: Used only where reliability is extremely important.
Where to used?
  • Military communication systems
  • Critical server networks
  • WAN backbones
  • Large data centers
  • Internet backbone routing

6. Hybrid Topology

Hybrid topology is a network layout that combines two or more different types of network topologies (such as star, bus, ring, mesh, etc.). It takes the advantages of each topology and forms one large, flexible network.

Hybrid topology is a combination of two or more topologies like star, bus, ring, or mesh. It is flexible and scalable but complex and expensive to set up.
Hybrid topology = Star + Bus + Ring + Mesh (any combination).

  • Combines multiple topologies
  • Flexible in design
  • Used in large, complex networks
Advantages
  • Highly Flexible: Can be customized according to the requirements of a network.
  • Scalable: Easy to expand by adding other topologies.
  • Strong and Reliable: Even if one topology fails, the others continue working.
  • Suitable for large organizations: Ideal for universities, corporates, and multinational networks.
Disadvantages
  • Very Expensive: Requires lots of cables, hubs, switches, routers, etc.
  • Difficult to design: Complex architecture requires expert planning.
  • High maintenance: More devices = more chances of failure.
  • Requires advanced management: Hard to troubleshoot large hybrid networks.
Where to used?
  • Schools and universities
  • Corporate offices
  • Large LAN and WAN networks
  • Data centers
  • Banks and multinational companies

Importance of Network Topology ?

Network Topology is important because it defines how devices are connected and how they communicate in the network. Here are some points that defines why network topology is important.

Network Performance: Upon choosing the appropriate topology as per requirement, it helps in running the network easily and hence increases network performance.

Network Reliability: Some topologies like Star, Mesh are reliable as if one connection fails, they provide an alternative for that connection, hence it works as a backup.

Network Expansion: Chosing correct topology helps in easier expansion of Network as it helps in adding more devices to the network without disrupting the actual network.

Network Security: Network Topology helps in understanding how devices are connected and hence provides a better security to the network.

MCQ

Network Topology

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