COMPUTER NETWORK NOTES, IOE, BSCCSIT,BCA
NETWORK TOPOLOGY
Network topology refers to the arrangement of nodes (computers, servers, routers, etc.) and the connections between them in a computer network. Different network topologies have distinct advantages and disadvantages, influencing factors such as performance, scalability, and fault tolerance. Here's an overview of some common network topologies:
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1. Bus Topology
Description:
- In a bus topology, all devices are connected to a single central cable, known as the bus or backbone.
- Data sent from a device is broadcast to all devices on the network.
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Advantages:
- Easy to set up and extend.
- Requires less cable length than a star topology.
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Disadvantages:
- Difficult to troubleshoot.
- A failure in the main cable (bus) can bring down the entire network.
- Limited cable length and number of nodes.
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2. Star Topology
Description:
- All devices are connected to a central hub or switch.
- The hub acts as a repeater for data flow.
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Advantages:
- Easy to install and manage.
- Failure of one cable does not affect other devices.
- Easy to detect faults and remove parts.
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Disadvantages:
- Requires more cable than bus topology.
- If the central hub fails, the whole network is inoperable.
- Higher cost due to the need for a hub.
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3. Ring Topology
Description:
- Each device is connected to exactly two other devices, forming a circular data path.
- Data travels in one direction (or two, in a dual ring topology).
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Advantages:
- Data packets travel at great speed.
- No need for a central hub.
- Reduced chances of data collisions.
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Disadvantages:
- Failure in any cable or device breaks the loop and can take down the network.
- Difficult to troubleshoot.
- Adding or removing devices disrupts the network.
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4. Mesh Topology
Description:
- Every device is connected to every other device on the network.
- Can be a full mesh (every device connected to every other) or partial mesh (some devices connected to multiple others).
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Advantages:
- High redundancy and reliability.
- Data can be transmitted simultaneously from different devices.
- Easy to isolate faults.
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Disadvantages:
- High cost due to the large number of cables and ports required.
- Complex to install and manage.
- Maintenance is difficult.
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5. Tree Topology
Description:
- A hybrid topology that combines characteristics of star and bus topologies.
- Hierarchical structure with a root node and all other nodes connected to it in a parent-child hierarchy.
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Advantages:
- Scalable and easy to manage.
- Fault isolation is simple.
- Expansion is easy by adding more nodes to the parent nodes.
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Disadvantages:
- If the root node fails, the entire network can become inoperative.
- Requires more cable than a bus topology.
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6. Hybrid Topology
Description:
- Combination of two or more different types of topologies.
- Example: Star-Ring, Star-Bus, etc.
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Advantages:
- Flexible and scalable.
- Can be designed to meet specific network requirements.
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Disadvantages:
- Complex design and installation.
- Expensive due to the combination of multiple topologies.
- Troubleshooting can be difficult.
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Comparison of Topologies
Topology |
Cable Required |
Scalability |
Redundancy |
Cost |
Installation |
Troubleshooting |
Bus |
Low |
Moderate |
Low |
Low |
Easy |
Difficult |
Star |
Moderate |
High |
Low |
Moderate |
Easy |
Easy |
Ring |
Low |
Low |
Moderate |
Low |
Moderate |
Difficult |
Mesh |
High |
High |
High |
High |
Difficult |
Easy |
Tree |
Moderate |
High |
Moderate |
Moderate |
Moderate |
Easy |
Hybrid |
Varies |
High |
High |
High |
Difficult |
Difficult |
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