Introduction to Computer Networks

How Does a Computer Network Work?

In Computer Networking, every single computer is considered a node and cables, fibre optics, or wireless communications are used to connect nodes. Routers and switches are also referred to as nodes in computer networks. 

The rules or protocols that specify how to transmit and receive electronic data over the links are followed by nodes. These rules are important to define the sending and receiving of informations. The connecting links enable communication and resource sharing among networked devices(nodes).

History of Computer Networks

The history of computer networks dates back to the 1960s when the U.S. Department of Defense's Advanced Research Projects Agency (ARPA) created the first wide area network (WAN), called the ARPANET. In the 1970s, organizations, universities, and research centers began to develop their networks. These networks were based on different technologies, such as Ethernet, which became the dominant LAN technology. In the 1980s, the use of personal computers increased, leading to the development of local area networks (LANs) in homes and businesses. LANs allowed devices to communicate with each other and share resources, such as printers and files. In the 1990s, the World Wide Web was developed, and the internet became more widely available to the public. This led to a rapid expansion of the internet and the development of new applications, such as email, instant messaging, and e-commerce. Since the 2000s, the internet has continued to evolve with the introduction of new technologies such as wireless networks, cloud computing, and the Internet of Things (IoT). Today, computer networks are an essential part of modern society, enabling communication, collaboration, and access to information on a global scale.

Features of Computer Networks

Computer networks have several features that enable them to provide various benefits. These features make computer networks a powerful tool for businesses, organizations, and individuals to collaborate, communicate, and share resources.

Here are some features of computer networks including:

1. Communication: Computer networks facilitate communication between devices, enabling them to share information and resources.
2. Reliability: Networks can be designed to provide redundancy and failover capabilities, ensuring that critical resources are always available.
3. Scalability: Networks can be expanded easily to accommodate new devices and users as an organization grows.
4. Mobility: Wireless networks allow devices to connect and communicate without needing physical cables, enabling greater mobility and flexibility.
5. Remote access: Networks enable users to access resources and information remotely, increasing productivity and efficiency.
6. Security: Networks can be secured with various measures, such as firewalls, encryption, and access control, to protect against unauthorized access and data breaches.
7. Centralized administration: Networks can be centrally managed, enabling administrators to control access, monitor usage, and apply policies across the network.

Types of Computer Network Architecture

1. Peer-to-peer network Architecture.
2. Client Server Network Architecture.

Let's discuss these architectures in detail.

Peer-to-Peer Network Architecture

Some characteristics of peer-to-peer architectures are given below:

1. The devices that are directly connected to one another are called peers. All the peers have equal rights, and there is no central authority.
    
2. This design is also known as decentralised architecture because there isn't a central authority to manage processes.
    
3. It is useful in settings with fewer computers and limited spaces.
    
4. Every peer has special rights to share resources, but this may cause problems if the computer holding the resource is down.

Client Server Network Architecture

Some characteristics of client-server architectures are given below:

1. As and when client computers demand access to shared resources or shared data, they establish a connection to the server.
    
2. There is no other device where the shared data is kept; it is all kept on the server.
    
3. Another name for this type of architecture is centralised architecture.
    
4. A server facilitates communication between all of the clients.
    
5. Every essential function, including network management and security, is handled by a server.

Computer Network Topologies

In computer networks, topology refers to the physical or logical layout of devices and connections in a network. The most common topologies are:

Bus Topology

In a bus topology, all devices are connected to a single cable, called a bus. Data is transmitted from one end of the cable to the other, and each device listens to the cable to determine if the data is intended for it. This topology is simple and inexpensive, but the entire network can be affected if the cable is damaged.

Star Topology

Each device is connected to a central hub in a star topology. Data is transmitted between devices through the hub. This manages traffic and ensures that data is sent only to the intended recipient. This topology is reliable and easy to operate, but it can be expensive due to the need for a central hub.

Mesh Topology

In this type of  topology, each device is connected to multiple other devices. Forms a network of interconnected nodes. Data can be transmitted through numerous paths. Provides redundancy and resilience in case of device failures. Mesh topology is complex and expensive. But it is commonly used in large networks that require high reliability.

Ring Topology

All devices are connected to two neighboring devices. Forms a circular loop in a ring topology. Data is transmitted in one direction only around the ring. Each device regenerates and forwards the signal to the next device. Ring topology is reliable and efficient. But the entire network can be affected if one device fails.

Tree Topology

In a tree topology, devices are arranged in a hierarchical structure. Where a central root node connects to multiple branches. Each of which connects to multiple leaves. Data is transmitted through the tree from the root node to the leaves. Every node manages traffic within its branch. Tree topology is scalable and easy to manage. With some benefits it brings some failure as well that is it can be vulnerable to failures in the central root node.

Hybrid Topology

This type of topology combines two or more of the other topologies. For example, a network might have a star topology at its core and a bus topology used to connect peripheral devices. Hybrid topology can provide the benefits of multiple topologies while minimizing their drawbacks.

Types of Enterprise Computer Networks

The types of enterprise computer networks are as follows:

1. Local Area Network
2. Wide Area Network
3. Cloud Networks.

Local Area Network

A local area network, or LAN, connects the computer systems in a small room or building. Within a bigger network, LANs can also be created virtually and logically. The enterprise network, for example, allows each department to run a mini LAN with many computers linked to the same switch but isolated from other departmental LANs.

LANs are frequently used for private purposes but they can also be utilised as testbed or small-scale prototype networks.

Wide Area Network

The technology that links your offices, data centres, cloud apps, and cloud storage is known as a wide-area network (WAN). WANs are typically set up by internet service providers (ISPs) and can be deployed as a private or public network.

In terms of the components and protocols used to carry data across the layers of the OSI model, WAN connectivity is different from LAN connectivity.

Cloud Networks

Cloud networks can be conceptualised as a WAN that has a number of private or shared subsets of networks that are spread among users of cloud computing services. Private, public, and hybrid cloud computing models may all be included in the cloud networks.
As an ideal trade-off between the cost, performance, and security given by various cloud models, you can use multi-cloud services to serve distinct services.

Different Computer Network Frameworks

Several different computer network frameworks or models define the layers of abstraction and functions within a network. The common network frameworks are:

OSI model

This OSI model has seven layers. Each layer is responsible for a specific aspect of network communication. The seven layers are:

1. Physical layer: These layers are responsible for the physical transmission of data over a network, such as transmitting bits over a cable or through the air.
2. Data link layer: These layers are responsible for reliable data transmission over a network. It provides error detection and correction and flow control mechanisms.
3. Network layer: Route the data packets from the source to the destination by providing logical addressing and routing functions.
4. Transport layer: This layer is responsible for reliable end-to-end data delivery between applications by providing error detection and correction, flow control, and congestion control mechanisms.
5. Session layer: Manage the communication sessions between applications by establishing, maintaining, and terminating connections between them.
6. Presentation layer: Representation of data in a format that the applications can understand by providing data translation, encryption, and compression functions.
7. Application layer: This layer is responsible for the interaction between the network and the applications by providing high-level communication services and protocols that enable applications to exchange data over the network.

You can read related articles such as Congestion Control in Computer Networks here.

TCP/IP Model

The TCP/IP model is a protocol suite that defines the communication protocols used on the Internet and many other computer networks. The TCP/IP model is compared to the OSI model, which has seven layers. However, the TCP/IP model is more widely used because it was designed specifically for the Internet and is more streamlined and efficient than the OSI model.

Coming to TCP/IP model is a four-layer model, which includes the following:

1. Application Layer: This layer defines the protocols that applications use to exchange data over the network. Examples of protocols in this layer include HTTP, SMTP, FTP, and DNS.
    
2. Transport Layer: This layer provides end-to-end communication services for applications. It is responsible for breaking data into smaller packets, ensuring the reliable delivery of packets, and reassembling packets at the receiving end. The two main protocols in this layer are UDP (User Datagram Protocol) and TCP (Transmission Control Protocol).
    
3. Internet Layer: This layer provides the routing and addressing services that enable packets to be sent from one network to another. It uses IP (Internet Protocol) to identify network devices and route packets between them.
    
4. Link Layer: This layer provides the physical interface between the network medium (such as Ethernet or Wi-Fi) and the device's network interface card (NIC). It is responsible for packaging data into frames and transmitting them over the physical medium.

Ethernet Model

The Ethernet model is a two-layer model that describes the functions of a LAN. The layers include the physical layer, which describes the physical components of a LAN, and the data link layer, which provides the protocol for communicating over the LAN.

Wireless Network Model

This type of network model describes the protocols and layers used in wireless networks. Includes the physical layer, application layer, transport layer, medium access control layer and network layer.

ATM Model

ATM stands for Asynchronous Transfer Mode model. This is a three-layer model used in high-speed networking. The layers include the physical layer, ATM layer, and adaptation layer.

Computer Network Devices

HUB

A hub is an essential network device. They are used to connect multiple devices in a network. It operates at the physical layer of the OSI model, which means that it transmits data in the form of electrical signals over the network. A hub receives incoming data from one device and forwards it to all other devices connected to the hub, regardless of the destination address of the data.

A hub is a simple and inexpensive network device. It can be used in small networks with few devices. It does not require any configuration or management and can be easily installed by simply connecting the network cables from the devices to the hub. However, a hub has several limitations:

1. Broadcasting: When a device sends data to the hub, the hub broadcasts the data to all other devices connected to it, which can cause network congestion and reduce network performance.
2. Collision: When two devices connected to a hub transmit data simultaneously, a collision occurs, and the data is lost. This can cause network delays and reduce network efficiency.
3. Security: A hub does not provide any security features, which means that all data transmitted over the network can be intercepted by any device connected to the hub.
    

Due to these limitations, hubs are rarely used in modern networks and have been largely replaced by switches, which are more efficient and provide better network performance and security.

SWITCH

A switch is a network device. Connect multiple devices in a network and forward data packets between them. Unlike a hub, which broadcasts all incoming data to all connected devices, a switch uses the destination MAC address of each data packet to determine the device to which it should be forwarded.

Switches operate at the data link layer of the OSI model, which means that they can analyze the MAC addresses of incoming data packets and make decisions about how to forward them. Switches have several advantages over hubs, including:

1. Reduced Network Congestion: Because switches forward data only to the devices that need it, they reduce network congestion and improve network performance. This is particularly important in large networks with many devices.
2. Improved Network Security: Switches can filter out data packets based on their source and destination MAC addresses, which helps prevent unauthorized network access. Some switches also support advanced security features like virtual LANs (VLANs) and port security.
3. Efficient Bandwidth Usage: Switches provide dedicated bandwidth to each connected device, which ensures that devices can transmit and receive data at their maximum capacity. This helps to improve network efficiency and reduce network delays.
4. Scalability: Switches can be easily expanded to support more devices and can be connected to create larger networks. This makes them ideal for use in both small and large networks.
    

Several types of switches are available, including unmanaged switches, managed switches, and layer three switches. Unmanaged switches are basic switches that do not require configuration or management and are ideal for small networks. Managed switches provide more advanced features and can be configured and controlled remotely. Layer 3 switches provide routing functionality in addition to switching and are used to connect multiple networks together.

ROUTER

A router is a network device connecting multiple networks and forwarding data packets between them. Routers operate at the network layer of the OSI model, which means that they use the destination IP address of each data packet to determine the network to which it should be forwarded.

Routers are essential for connecting networks, such as a local area network (LAN), to the internet and are used in small and large networks. Routers provide several benefits, including:

1. Network Segmentation: Routers can divide a large network into smaller segments, which helps to improve network performance and security. Each network segment can have its subnet and set of IP addresses, which makes it easier to manage network traffic.
2. Improved Network Security: Routers can use firewalls and other security measures to protect networks from unauthorized access and security threats. They can also be used to create virtual private networks (VPNs), which provide secure connections between remote networks.
3. Centralized Management: Routers can be managed centrally, making configuring and monitoring network settings and devices easier.
    

Several types of routers are available, including home routers, enterprise routers, and edge routers. Home routers are typically used in small networks and provide basic routing and firewall functionality. Enterprise routers are used in larger networks and provide more advanced routing and security features. Edge routers are used in service provider networks and provide high-speed routing and forwarding capabilities.
 

Must Read Subnetting in Computer Networks

Computer Networking Functions

Computer networks perform several essential functions that enable communication, data transfer, and resource sharing. These functions are essential for the efficient operation of modern computer networks and would allow organizations to communicate, collaborate, and share resources more effectively. Here are some of the essential functions of computer networks:

Communication

Networks enable communication between devices and users, allowing them to exchange messages, data, and multimedia content.

Resource sharing

Networks enable the sharing of resources such as printers, scanners, storage devices, and software applications, making them more efficient and cost-effective.

Data transfer

Networks enable data transfer between devices and users, enabling real-time data sharing and collaboration.

Security

Networks provide security features such as authentication, access control, and encryption to protect data and devices from unauthorized access and data breaches.

Network management

Networks require management and monitoring to ensure they operate correctly and efficiently. Network administrators are responsible for configuring, maintaining, and troubleshooting networks.

Internet connectivity

Networks enable devices to connect to the internet, providing access to online resources and services.

Remote access

Networks enable remote access to devices and resources, allowing users to work from anywhere with an internet connection.

Scalability

Networks enable organizations to add or remove devices as needed, allowing them to scale their networks to meet changing needs.

Redundancy

Networks can be designed to provide redundancy and fault tolerance, ensuring critical systems remain operational in case of hardware or software failures.

Applications of Computer Network

Computer networks have various applications across different industries and domains. Computer networks flexibility and scalability makes them an essential tool for modern businesses and organizations to communicate, collaborate, and share resources. Some typical applications of computer networks are:

Communication

Networks help us to communicate between individuals and organizations. It allows us to exchange messages, data, and multimedia content.

File sharing

Networks enable users to share files and resources like printers, scanners, and storage devices, increasing efficiency and productivity.

E-commerce

Networks also enable online transactions. Online transactions could be buying and selling goods and services, and allow the creation and management of online market places.

Education

With the help of Networks users can access remote learning. It allows students to access educational resources and collaborate with teachers and other students across the world.

Entertainment

Due to Networks users can access multimedia content, such as music, movies, and video games, and allow for streaming and online gaming.

Health care

Networks enable telemedicine and remote patient monitoring. Also allow doctors and healthcare providers to diagnose and treat patients remotely.

Transportation

With the help of Networks, real-time tracking and monitoring of vehicles is possible. It enabled logistics and transportation companies to optimize their operations and improve efficiency.

Banking and finance

Networks enable online banking, stock trading, and other financial transactions and allow financial institutions to securely manage and process large volumes of data.

Characteristics of Computer Networks

Some characteristics of computer networks are given below:

1. Topology: The physical arrangement of devices and nodes in a network. Like bus, star, ring, or mesh topology.
2. Security: The protocols to protect a network from unauthorized access, data breaches, and other security threats.
3. Network architecture: The design and structure of a network, including its layers, technologies and protocols.
4. Reliability: The ability of a network to maintain consistent performance. Even in the face of hardware or software failures or attacks.
5. Latency: The time it takes for data to travel between devices on a network. That can affect the performance of real-time applications like video conferencing or online gaming.
    

Also see, Basic Networking Commands

Frequently Asked Questions

What is meant by a computer network?

A computer network is a collection of interconnected computers and other devices that communicate with  each other,  and share information, data, and resources. Networks through which computer shares information can be LAN, WAN, or MAN.

How many types of computer networks are there?

Some most common types of networks includes  LANs (Local Area Network), WANs (Wide Area Network), MANs (Metropolitan Area Network). LANs cover a small geographical area, while WANs and MANs can operated by multiple organizations or service providers.

What are the uses of computer networks?

Computer networks have various applications across different industries and domains. Computer network's provide flexibility and scalability makes them an essential tool for modern businesses and organizations to communicate, collaborate, and share data, infomation, and other useful resources.

Conclusion

In this article, we have discussed Computer Networks. We discussed the basics of computer networks, what is computer networks, their history, Models, Devices, features, advantages, limitations of java, and much more.

In conclusion, Computer networks help us to communicate, transfer data, and share resources between devices and users. They have become integral to modern society, enabling businesses, governments, and individuals to connect and collaborate globally. There are other types of networks, including LANs, WANs, and MANs, each have advantages and disadvantages. Despite the challenges and limitations of computer networks, they continue to evolve and improve, driving innovation and progress in many fields.

Recommended Readings:

• Memory hierarchy in computer network
• Addressing Modes of 8086
• Repeater in Computer Network
• Register in Computer
• Digital Subscriber Line
• What are payloads
   

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