Introduction to Computer Network for Beginners

A computer network is a group of devices connected through a transmission medium, network adapters, and network operating systems that support communication protocols. It is any collection of independent computers that exchange information with each other over a shared communication medium. The medium used to transmit data across the network is referred to as transmission media. It can be wired or wireless.

What is Computer Networking?

It is the art of connecting two or more devices to share peripherals (resources) such as printers, scanners, faxes, photocopiers, and storage devices among others.

Notes on Computer Network

• Protocols are rules that define how two or more computers systems communicate in a network.
• A stand-alone computer is a computer that is not connected to another.
• Before networks became widespread, computers operated in a stand-alone environment. Information was shared by print outs or copying data to a floppy disk, CD, and passing it to others. This method of data sharing is called sneakernet. This play on words stems from the idea that a person is using their feet, i.e., sneakers, to transfer data instead of through the Internet or an organization’s intranet. If others made changes to the document, there was no easy way to merge the changes.

Computer Network Components

Components that make a computer network can be classified into two categories:-

• Hardware
• Software

Hardware Components

• The sender (source): – This is the computer or device that is sending data.
• The receiver (Destination): – This is the computer or any other device that is intended to receive the transmitted data.
• Transmission medium: – provides passage of data and it can be in the form of cable or wireless media such as infrared, microwave and radio.
• Client: – A client is a computer connected on the network accessing the shared resources from a server.
• Servers: – They are powerful computers that provide shared resources such as storage, printing, email etc., which allows the client to access information on a network. The server machine often has a faster CPU, more memory, and more disk space than a typical client machine.
• Node:– A node is a device that is connected as part of a computer network for instance computer, PDA, Cell phone, router, switches, servers, printers etc. and can communicate on the network.
• Host:- a) This is a computer system accessed by a user working at a remote location. The computer that contains the data is called the host, while the computer at which the user sits is called the remote terminal.

b) A computer that is connected to a TCP/IP network, including the Internet. Each host has a unique IP address.

Computer Network Components Continued

• Segment: – It is a part or unit of a larger network that is linked by a connecting device such as a hub or router.
• Router – This is the piece of network hardware that allows communication between your local home network, for instance, your personal computer and the internet.
• Hub – This is a device that splits a network connection into multiple computers. It is like a distribution centre. When a computer requests information from a network or a specific computer, it sends the request to the hub through a cable. The hub will receive the request and transmit it to the entire network.
• Switch – A network switch is networking hardware that connects devices on a computer network by using packet switching to receive and forward data to the destination device. A switch is like a Hub but built-in with advanced features. It uses physical device addresses in each incoming messages so that it can deliver the message to the right destination or port.
• Backbone: – A link (usually fast) between segments of a network. The backbone or trunk segment is the main cable from which transceiver cables are connected to computers, repeaters and bridges.
• NIC: – Network Interface Card, it is a device that acts as the physical interface (link) between the computers and the network cables.

Software Components

The software allows computers to communicate over a computer network. They control a network and its message (e.g. packets) traffic and queues. The software includes:-

1. Network Operating System (NOS): – They run on servers, giving the server the ability to share resources e.g. Windows NT, Novel Netware, UNIX, Linux etc.
2. Client Application Software: –This is the software that allows a client to access shared resources.

Computer Network Architecture

Computer Network Architecture defines the physical and logical design of the software, hardware, protocols, and media in a network setup. In simple terms, it is how computers are organized and how tasks are allocated in network design.

The two types of network architectures used are:

• Peer-To-Peer network
• Client/Server network

Peer to Peer Network

When nodes or workstations perform the same communication functions, they are referred to as peers. In this architectural design, both server and client operations are performed by the same computer. Each user administers his or her workstation and the resources in it. In a peer-to-peer network, there are no dedicated servers, and there is no hierarchy among the computers. All the computers are equal and therefore are known as peers. Each computer functions as both a client and a server, and there is no administrator responsible for the entire network. Data that is to be shared on the network is determined by the user.

The user of the device manages its security. This model is not quite secure. It is suited for a small computer network (with 10 computers or less) where users do not want to share files.

User’s files are decentralized meaning they are not stored in a single location.

Criteria for Selecting Peer To Peer Network Architecture

• Where ten or fewer users will be sharing resources.
• When no server is available.
• Nobody has the time or knowledge to act as a network administrator.
• There is little or no concerns about security (security in data processing is the ability to protect data from unauthorized access or, theft or damage).
• The organization and the network will experience only limited growth within the foreseeable future.

Advantages of Using Peer To Peer

• They are easy to configure
• Computers communicate easily.
• They don’t require additional server hardware or software
• Users can manage their resources.
• They don’t require a network administrator
• They reduce the total cost of the network setup.

Disadvantages of Using Peer To Peer

• They provide a limited number of connections for shared resources.
• Computers with shared resources suffer from sluggish performance.
• They don’t allow for central management.
• Users are responsible for managing resources. These resources include data in shared directories, printers, fax cards, and so on.
• They offer very poor security.

Client Server Networks

It is a network architecture that offers centralized access to services and devices. One computer plays the role of a server. It is the most common type of network architecture today that provides centralized data storage, security, manning of applications and network administration. A client is a computer that connects to the server.

A client-server network may have more than one server, each dedicated to handling a specific function.

Functions of the Server

• Data storage
• Monitoring network traffic
• Email services
• Print jobs
• Handling security
• Hosting shared applications
• Domain name services
• Managing an internet connection
• Scheduling and running backups
• Storing usernames and passwords to control access
• Assigning levels of access to resources

Advantages

• They are best suited for ten or more users.
• Security: – All major server-based systems provide sophisticated security.
• Administration: – Servers are centralized making them easier to manage.
• Stability: – Server-based systems are designed to support a wide range of organization sizes. Additional servers are added to increase capacity.
• Client-server networks offer centralized backup where data can be stored in one server.
• Flexibility – New technology can be easily integrated into the system.
• Interoperability – All components (client/network/server) work together.
• Accessibility – Server can be accessed remotely and across multiple platforms.
• Faster performance as each computer is only fulfilling one role.

Disadvantages

• Cost: – More expensive in terms of hardware and network operating system.
• Complexity: – Experienced system administrators are required to manage the systems.
• Dependence: – When the server goes down, most and perhaps crucial operations will cease across the network.