What is a Computer Network?

A computer network connects multiple devices to share information, resources, and services. These networks differ based on their size, structure, and purpose.

Types of Computer Networks

1. Personal Area Network (PAN)

A Personal Area Network (PAN) is designed for personal use. It connects devices within a small range, usually a few meters. Examples include Bluetooth, infrared devices, or USB connections. PANs are ideal for home offices or personal device synchronization.

2. Local Area Network (LAN)

• LAN is a network that connects computers in a localized area, like an office or school. It is efficient, fast, and allows resource sharing, such as printers and file servers. Ethernet and Wi-Fi are common LAN technologies.
• Generally, it connects two or more personal computers through a communication medium such as coaxial, twisted-pair cables, etc. A LAN can use either wired or wireless mode of communication. The LAN which entirely uses wireless media for communication can be termed as WLAN (Wireless Local Area Network).

Following are the advantages of a LAN:
1. File transfer and file access
2. Resource or peripherals sharing
3. Personal computing
4. Document distribution
5. Easy to design and troubleshoot
6. Minimum propagation delay
7. High data rate transfer
8. Low error rate
9. Easily scalable(devices can be added or removed very easily)

The following are the disadvantages of a LAN:

1. Equipment and support may be costly
2. Some hardware devices may not inter-operate properly

3. Metropolitan Area Network (MAN)

• MAN covers a larger geographical area than LAN but is smaller than WAN. It connects multiple LANs within a city or metropolitan area. Universities and city government offices frequently use MAN for interconnection.
• A Metropolitan Area Network is a bigger version of LAN that uses similar technology as LAN. It spans over a larger geographical area of about 50km such as a town or an entire city. It can be connected using an optical fiber cable as a communication medium. Two or more LANs 's can also be connected using routers to create a MAN.
  The best example of MAN is the cable television network that spans over the whole city. A MAN can be either a public or privately owned network. The protocols that are used in MAN are RS-232, Frame Relay, ISDN, etc.

The uses of MAN are as follows:

1. MAN can be used for connecting the various offices of the same organization, spread over the whole city.
2. It can be used for communication in various governmental departments.

Following are the advantages of using MAN:

1. Large geographical area cover as compared to LAN
2. High-speed data connectivity
3. The Propagation delay of MAN is moderate

Following are the disadvantages of MAN:

4. It is hard to design and maintain a MAN
5. MAN is less fault-tolerant
6. It is costlier to implement
7. Congestions are more in a MAN

4. Wide Area Network (WAN)

• A WAN spans large distances, often connecting countries or continents. It consists of multiple LANs and MANs. The internet is the most common example of a WAN. Organizations use WANs to connect their global offices.
• A Wide Area Network is the largest spread network. It spans over very large distances such as a country, continent, or even the whole globe. Two widely separated computers can be connected very easily using WAN. For Example, the Internet.
• A WAN may include various Local and Metropolitan Area Networks. The mode of communication in a WAN can either be wired or wireless. Telephone lines for wired and
  satellite links for wireless communication can be used in a wide area network. In other words, WAN provides long-distance transmission of data, voice, image, and video,
  over a large geographical area. A WAN may span beyond the 100km range. It may be privately or publicly owned.

Wild Area Network

Features of WAN:

• It is not restricted to a geographical location; it is spread all over the world.
•  Satellite links and microwave system is used for connectivity.
•  The technology is high-speed and expensive.
• Data transmission is slower in comparison to LANs.
  

  Advantages of WAN:

• It covers large geographical area.
•  Ease updates to the data and information.
• The scope of activities is not limited.
  

  Disadvantages of WAN:

• The cost is higher.
• More associated errors occur.
•  We need to invest in a good firewall system.
• High-security challenges from hackers.

5. Campus Area Network (CAN)

• A CAN connects networks within a specific campus, like a university or corporate setting. It provides high-speed connectivity for devices within the campus premises.

6. Storage Area Network (SAN)

• A SAN is a specialized network designed to provide high-speed access to storage devices. It’s mainly used in data centers where large-scale storage is essential.

7. Virtual Private Network (VPN)

• VPNs are secure networks that use encryption to connect remote users to a private network. They are widely used for remote work and secure browsing.

8. Global Area Network (GAN)

• A GAN is designed for global communication. It uses satellites and wireless technology to interconnect multiple WANs across the globe.

Advantages of Computer Networks

• Resource Sharing: Networks enable the sharing of printers, files, and internet connections.
• Data Communication: They facilitate instant communication via emails, video calls, and messaging.
• Scalability: Networks can expand easily to accommodate more devices.
• Cost Efficiency: Shared resources reduce overall operational costs.

Applications of Computer Networks

• Business Operations: Supports collaboration, data storage, and customer interaction.
• Education: Provides access to e-learning platforms and digital resources.
• Healthcare: Enables telemedicine and electronic health records.
• Government Services: Facilitates efficient public service delivery.

What is Topology?

Topology in networking refers to the layout or arrangement of nodes and connections within a network. It defines how devices such as computers, routers, switches, and other hardware are physically and logically connected to transmit data efficiently. Network topology impacts the performance, scalability, and reliability of a system, making it an essential aspect of network design.

Key Elements of Topology

1. Nodes: Devices or endpoints, such as computers or servers.
2. Links: The communication pathways between nodes, either wired or wireless.
3. Protocols: Rules that govern data communication within the network.

Types of Topology

Topology can be broadly classified into two categories: Physical Topology and Logical Topology.

1. Physical Topology

This type defines the physical arrangement of devices and cables in the network. It is primarily concerned with the physical layout of the hardware.

Common Physical Topologies:

• Bus Topology
• Star Topology
• Ring Topology
• Mesh Topology
• Tree Topology
• Hybrid Topology

2. Logical Topology

Logical topology focuses on how data flows within the network, regardless of its physical design. It deals with the conceptual layout of data transmission paths.

Common Logical Topologies:

• Point-to-Point Topology
• Peer-to-Peer Topology

Detailed Overview of Topology Types

1. Bus Topology

• Bus topology is one of the simplest types where all nodes are connected to a single communication line or backbone.
• Bus topology is the simplest kind of topology in which a common bus or channel is used for communication in the network. The bus is connected to various taps and droplines. Taps are the connectors, while droplines are the cables connecting the bus with the computer. In other words, there is only a single transmission line for all nodes.
• In this topology, the bus acts as the backbone of the network, which joins every computer and peripherals in the network. Both ends of the shared channel have line terminators.
• The data is sent only in one direction and as soon as it reaches the end, the terminator removes the data from the communication line(to prevent signal bounce and data flow disruption).

Advantages:

• Cost-effective as it requires fewer cables.
• Easy to implement and expand.
• Less cabling is required.

Disadvantages:

• Limited scalability.
• High chance of network failure if the main cable is disrupted.
• Efficiency is less when nodes are more(strength of signal decreases).

2. Star Topology

• In star topology, all nodes are connected to a central hub or switch. The hub acts as a mediator for data transmission.
• In a star topology, the hub and switch act as a server, and the other connected devices act as clients. Only one input-output port and one cable are required to connect a node to the central device.
• This topology is better in terms of security because the data does not pass through every node.

Advantages:

• High reliability since individual failures do not affect the network.
• Easy to troubleshoot and manage.
• Easy to reconfigure and upgrade(configured using a central device).

Disadvantages:

• The central hub is a single point of failure.
• Higher installation costs due to additional cabling.
• The number of devices in the network is limited(due to limited input-output port in a central device).

3. Ring Topology

• Ring topology connects nodes in a closed loop, where each device is connected to two others.
• Ring topology is a type of network configuration where devices are connected circularly, forming a closed loop. In this setup, each device is connected to exactly two other devices, creating a continuous pathway for data transmission.

Advantages:

• Equal distribution of network load.
• Easy to identify faults.
• Each node gets the same access time.
• Less Cabling Required.

Disadvantages:

• A break in the ring can disrupt the entire network.
• Difficult to reconfigure.

4. Mesh Topology

• In a mesh topology, every node is connected to every other node.
• Mesh topology is a computer network topology in which nodes are interconnected with each other. In other words, direct communication takes place between the nodes in the network.

Advantages:

• Extremely reliable due to multiple pathways.
• Supports high traffic volumes.
• Very fast communication.

Disadvantages:

• High setup costs due to extensive cabling.
• Complex installation and maintenance.

5. Tree Topology

• Tree topology is a hierarchical arrangement of nodes, combining characteristics of bus and star topologies.
• In a tree topology, the whole network is divided into segments, which can be easily managed and maintained. There is a main hub and all the other sub-hubs are connected in this topology.

Advantages:

• Scalable and ideal for large networks.
• Easy to manage with segmented networks.
• A Large number of nodes can be connected directly or indirectly.

Disadvantages:

• Complex structures can be difficult to troubleshoot.
• The backbone cable is a critical point of failure.
• Cabling and hardware costs are high.

6. Hybrid Topology

• Hybrid topology integrates two or more different types of topologies into a single network.
• A hybrid topology is a computer topology that is a combination of two or more
  topologies. In practical use, they are the most widely used.

Advantages:

• Highly flexible and scalable.
• Combines the benefits of multiple topologies.
• It provides flexibility to modify the network according to our needs.

Disadvantages:

• Complex and expensive to set up.
• Troubleshooting requires expertise.
• A multi-Station Access Unit (MSAL) is required.

Choosing the Right Topology

Selecting the right topology depends on several factors:

1. Network Size: Larger networks often require scalable topologies like tree or hybrid.
2. Budget: Cost-effective solutions like bus topology are suitable for smaller networks.
3. Reliability Requirements: Mesh topology is ideal for networks where reliability is critical.
4. Future Scalability: Hybrid and tree topologies offer flexibility for expansion.

Impact of Topology on Network Performance

Network topology has a direct influence on the following aspects:

1. Data Flow: Efficient design minimizes latency and enhances speed.
2. Fault Tolerance: Robust topologies ensure continuity in case of failures.
3. Scalability: A well-chosen topology supports future growth.
4. Cost Efficiency: Optimized design reduces setup and maintenance costs.

Conclusion

Understanding network topology and its various types is essential for designing systems that meet performance, scalability, and reliability requirements. Whether you opt for the simplicity of a bus topology or the robustness of a mesh topology, your choice should align with your network’s specific needs.