What is Computer Network?
A computer network can be described as a system of interconnected devices commonly referred to as nodes that can communicate using some common set standards or rules called protocols which are used to transmit information over physical or wireless technologies.
These devices communicate to exchange resources and services. These devices are connected using physical media such as copper, fibre optics or they can also be connected wireleslys.
In Computer Science, networking is a branch that deals with the architecture, creation, maintenance, and security of computer networks. It is a combination of computer science, computer engineering, and telecommunication.
Key Components of a Computer Network
Most basic networks are designed to connect users and enable them to access various resources, like the Internet, printers and other shared files. Networks are comprised of four basic elements: hardware, software, protocols and the connection medium. All data networks are comprised of these elements, and cannot function without them.
- Hardware Components:- The backbone of any network is the hardware that runs it. Network hardware includes things like network cards, routers or network switches, modems, and Ethernet repeaters.Without this hardware, computers have no means of accessing a network. Network cards give computers direct access to network media and enable them to connect to other equipment, including routers, switches, modems and repeaters. Routers or switches allow a single network connection from a modem to be divided between several computers
- Networking Software:- Network software refers to a wide range of software that streamlines the operations, design, monitoring, and implementation of computer networks. The primary form of networking software is protocols that refers to a software which instructs network devices on how to connect to the network and how to interact and communicate with one another. Networking software eliminate the dependence on hardware by streamlining communications across multiple devices, locations, and systems.
- Client Devices/Nodes :- Client devices or also called nodes are the computers and mobile devices connected to the network. Client devices are vital components of a network, as without clients requiring access the network is essentially pointless.
- Connection Media: –This refers to the medium used to connect the nodes of a network varies with the type of network. Its categorised into two that is wired and wireless media.
Wired: Examples of wired technologies used in networks include coaxial cables, phone lines, twisted-pair cabling, and optical fibres.
Wireless: Network connections can also be established through radio or other electromagnetic signals. This kind of transmission is called ‘wireless’. The most common examples of wireless links include communication satellites, cellular networks, and radio and technology spread spectrums.
Key objectives of Computer Network
- Resource sharing: – A network allows data and other resources such as files, printers and media to be accessible to every pertinent user in an organisation.
- Streamlined communication: Networks are critical for email, instant messaging, and faxing capabilities. Employees can share files, view each other’s work, sync their calendars, and exchange ideas more effectively
- Organization: – Networks centralize data and make it more accessible, which increases the efficiency and speed with which this information can be accessed.
- Resource availability & reliability: – A network ensures that resources are not present in inaccessible silos and are available from multiple points.
- Secured remote access: – Computer networks promote flexibility, which is important in uncertain times like now when natural disasters and pandemics are ravaging the world. A secure network ensures that users have a safe way of accessing and working on sensitive data, even when they’re away from the company premises
Types of Computer Network
- Local Area Network
A local area network (LAN) is a group of computers that are confined to a small geographic area, usually one building. Setting up a LAN requires computers with network adapters, central connecting devices to connect those computers together, and a numbering scheme (such as IP addresses) to differentiate from one computer to the next. Usually, LANs utilize one of several Ethernet standards. Ethernet is a set of rules that govern the transmission of data between network adapters and various central connecting devices.
- Campus area network (CAN)
Campus area networks are a collection of interconnected LANs. They are used by larger entities such as universities and governments.
- Metropolitan area network (MAN)
A metropolitan area network (MAN) is a computer network that is larger than a single building local area network (LAN) and is located in a single geographic area like a city
- Wide area network (WAN)
Wide area networks cover larger areas such as large cities, states, and even countries and are always established with leased telecommunication circuits. Businesses, as well as schools and government entities, use wide area networks to relay data to staff, students, clients, buyers and suppliers from various locations around the world
Network topology refers to the pattern or hierarchy in which nodes are connected to each other. Topology may also describe how the data is transferred between nodes in a network.
There are two types of network topologies: physical and logical. Physical topology emphasizes the physical layout of the connected devices and nodes, while the logical topology focuses on the pattern of data transfer between network nodes.
The physical and logical network topologies of a network do not necessarily have to be identical. However, both physical and network topologies can be categorized into five basic models:
- Bus Topology:- All the devices/nodes are connected sequentially to the same backbone or transmission line. This is a simple, low-cost topology, but its single point of failure presents a risk.
- Star Topology:- All the nodes in the network are connected to a central device like a hub or switch via cables. Failure of individual nodes or cables does not necessarily create downtime in the network but the failure of a central device can. This topology is the most preferred and popular model.
- Ring Topology:- All network devices are connected sequentially to a backbone as in bus topology except that the backbone ends at the starting node, forming a ring. Ring topology shares many of bus topology’s disadvantages so its use is limited to networks that demand high throughput.
- Tree Topology:- A root node is connected to two or more sub-level nodes, which themselves are connected hierarchically to sub-level nodes. Physically, the tree topology is similar to bus and star topologies; the network backbone may have a bus topology, while the low-level nodes connect using star topology.
- Mesh Topology:- The topology in each node is directly connected to some or all the other nodes present in the network. This redundancy makes the network highly fault-tolerant but the escalated costs may limit this topology to highly critical networks.
Important terms and concepts
The following are some common terms to know when discussing computer networking:
- IP address: An IP address is a unique number assigned to every device connected to a network that uses the Internet Protocol for communication. Each IP address identifies the device’s host network and the location of the device on the host network. When one device sends data to another, the data includes a ‘header’ that includes the IP address of the sending device and the IP address of the destination device.
- Nodes: A node is a connection point inside a network that can receive, send, create, or store data. Each node requires you to provide some form of identification to receive access, like an IP address. A few examples of nodes include computers, printers, modems, bridges, and switches. A node is essentially any network device that can recognize, process, and transmit information to any other network node.
- Routers: A router is a physical or virtual device that sends information contained in data packets between networks. Routers analyse data within the packets to determine the best way for the information to reach its ultimate destination. Routers forward data packets until they reach their destination node.
- Switches: A switch is a device that connects other devices and manages node-to-node communication within a network, ensuring data packets reach their ultimate destination. While a router sends information between networks, a switch sends information between nodes in a single network. When discussing computer networks, ‘switching’ refers to how data is transferred between devices in a network
How does Computer network works?
A computer network is a set of computers (desktops, laptops, servers, etc.) and other computing devices (smartphones, tablets, etc.) which are connected together with wires, optical fibres or through wireless links so that the various devices can communicate with each other, exchange data and share resources. In addition to the computing devices, there are many network enabled peripherals like printers and scanners which also connect to the network.
All these devices or nodes use a wired or wireless network interface controller, also termed as network card or wireless card, to connect to the network. This controller has the electronic circuits required for network communication. These network cards of various devices are connected through wires to a switch or a hub (though it is rarely used now) while the wireless cards connect to the network using access points.
Computer networks work according to a set of well-defined rules. All the devices connected to a network follow these rules for communicating with each other. These rules are termed as protocols.
The operating systems (Linux, Windows, Mac OS X, Android, etc.) running on computers have special software, commonly called network stack, which takes over from the user applications and carries out all the network communication related processing until the data is sent out from the network interface controller. The network stack similarly processes the incoming data from the network and hands it over to the applications.
The client-server architecture refers to a system where hosts computer normally referred to as the server delivers, and manages most of the resources and services that the client requests. In this model, all requests and services are delivered over a network through an established communication channel or session
Client-server architecture typically features multiple users’ workstations, PCs, or other devices, connected to a central server via an Internet connection or other network. The client sends a request for data, and the server accepts and accommodates the request, sending the data packets back to the user who needs them.
Examples of Client-Server Architecture
- Web servers: These high-performance servers host many different websites, and clients access them through the Internet. Here, a home user who is connecting to the Internet. When this person wants to go to a Web site such as Bing, he or she opens a web browser and types http://www.bing.com/ (or one of many shortcuts). The web browser is the client application. Bing’s web server is obviously the “server.” It serves the web pages filled with glorious HTML code. The client computer’s web browser decodes the HTML and fills the user’s display with Internet goodness.
- Email Clients: Another example is if you use an email program like Microsoft Outlook. Outlook is the client application; it connects to a mail server, most likely an SMTP server, perhaps run by Microsoft Exchange Server