Table of contents
What is Computer networking?
Computer networking refers to interconnected computing devices that can exchange data and share resources with each other. These networked devices use a system of rules, called communications protocols, to transmit information over physical or wireless technologies.
How does a computer network work?
Nodes and links are the basic building blocks in computer networking. A network node may be data communication equipment (DCE) such as a modem, hub or, switch, or data terminal equipment (DTE) such as two or more computers and printers. A link refers to the transmission media connecting two nodes. Links may be physical, like cable wires or optical fibers, or free space used by wireless networks.
In a working computer network, nodes follow a set of rules or protocols that define how to send and receive electronic data via the links. The computer network architecture defines the design of these physical and logical components. It provides the specifications for the network’s physical components, functional organization, protocols, and procedures.
What do computer networks do?
Computer networks were first created in the late 1950s for use in the military and defense. They were initially used to transmit data over telephone lines and had limited commercial and scientific applications. With the advent of internet technologies, a computer network has become indispensable for enterprises.
Modern-day network solutions deliver more than connectivity. They are critical for the digital transformation and success of businesses today. Underlying network capabilities have become more programmable, automated, and secure.
Modern computer networks can:
Operate virtually
The underlying physical network infrastructure can be logically partitioned to create multiple "overlay" networks. In an overlay computer network, the nodes are virtually linked, and data can be transmitted between them through multiple physical paths. For example, many enterprise networks are overlaid on the internet.
Integrate on a large scale
Modern networking services connect physically distributed computer networks. These services can optimize network functions through automation and monitoring to create one large-scale, high-performance network. Network services can be scaled up or down based on demand.
Respond quickly to changing conditions
Many computer networks are software-defined. Traffic can be routed and controlled centrally using a digital interface. These computer networks support virtual traffic management.
Provide data security
All networking solutions come with in-built security features like encryption and access control. Third-party solutions like antivirus software, firewalls, and antimalware can be integrated to make the network more secure.
Why do we need Computer Networks?
To share computer files
Networks enable users to share files with others. For example, in a company, one file is to be shared by multiple branches. When we locate this file on the network system, all the branches can use this file.
To share computer equipment
Laser printers and large hard-disk drives can be expensive. Networks enable users to share such equipment by networking microcomputers or workstations together.
To enable unlike computer equipment to communicate
A company with computers of multiple uses using several operating systems, including MS-DOS, UNIX, WINDOWS 95, and Apple DOS, cannot share files from one computer to another unless arranged using a Networking operating system including Network 4.1 or Windows NT 4.0.
To improve communication speed and accuracy
Sending messages through networks is virtually instantaneous, and there is also less chance of a message being lost.
To reduce the cost of data transfer
The cost of transfers of files using computers associated with networks is less expensive than other traditional means like telegrams.
Verify Data Transfer
Fluctuations of costs in foreign exchange and shares can be broadcasted promptly using the channel of computer communications. The transmission can be increased and checked at any occurrence of time.
High Reliability
All files can be recreated on a few machines, and therefore if one of them is unavailable (because of hardware failure), the different copies can be used.
What is network topology?
The arrangement of nodes and links is called network topology. They can be configured in different ways to get different outcomes. Some types of network topologies are:
Bus topology
Each node is linked to one other node only. Data transmission over the network connections occurs in one direction.
Ring topology
Each node is linked to two other nodes, forming a ring. Data can flow bi-directionally. However, single node failure can bring down the entire network.
Star topology
A central server node is linked to multiple client network devices. This topology performs better as data doesn’t have to go through each node. It is also more reliable.
Mesh topology
Every node is connected to many other nodes. In a full mesh topology, every node is connected to every other node in the network.
Key Components of a Computer Network
From a broader lens, a computer network is built with two basic blocks: nodes or network devices and links. The links connect two or more nodes with each other. The way these links carry the information is defined by communication protocols. The communication endpoints, i.e., the origin and destination devices, are often called ports.
1. Network Devices
Network devices or nodes are computing devices that need to be linked in the network. Some network devices include:
1. Computers, mobiles, and other consumer devices: These are end devices that users directly and frequently access. For example, an email originates from the mailing application on a laptop or mobile phone.
2. Servers: These are application or storage servers where the main computation and data storage occur. All requests for specific tasks or data come to the servers. Routers: Routing is the process of selecting the network path through which the data packets traverse. Routers are devices that forward these packets between networks to ultimately reach the destination. They add efficiency to large networks.
3. Switches: Repeaters are to networks what transformers are to electricity grids—they are electronic devices that receive network signals and clean or strengthen them. Hubs are repeaters with multiple ports in them. They pass on the data to whichever ports are available. Bridges are smarter hubs that only pass the data to the destination port. A switch is a multi-port bridge. Multiple data cables can be plugged into switches to enable communication with multiple network devices.
4. Gateways: Gateways are hardware devices that act as ‘gates’ between two distinct networks. They can be firewalls, routers, or servers.
5. Routers: Routers help you to connect with multiple networks. It enables you to share a single internet connection with multiple devices and saves money. This networking component acts as a dispatcher, which allows you to analyze data sent across a network. It automatically selects the best route for data to travel and send it on its way.
6. Clients: Clients are computer devices which access and uses the network as well as shares network resources. They are also users of the network, as they can send and receive requests from the server.
7. Transmission Media: Transmission media is a carrier used to interconnect computers in a network, such as coaxial cable, twisted-pair wire, and optical fiber cable. It is also known as links, channels, or lines.
8. Access points: Access points allow devices to connect to the wireless network without cables. A wireless network allows you to bring new devices and provides flexible support to mobile users.
9. Shared Data: Shared data are data which is shared between the clients such as data files, printer access programs, and email.
10. Network Interface Card: Network Interface card sends, receives data, and controls data flow between the computer and the network.
11. Local Operating System: A local OS which helps personal computers to access files, print to a local printer and uses one or more disk and CD drives which are located on the computer.
12. Network Operating System: The network operating system is a program which runs on computers and servers. It allows the computers to communicate via network.
13. Protocol: A protocol is the set of defined rules that allows two entities to communicate across the network. Some standard protocols used for this purpose are IP, TCP, UDP, FTP, etc.
14. Hub: Hub is a device that splits network connection into multiple computers. It acts a distribution center so whenever a computer requests any information from a computer or from the network it sends the request to the hub through a cable. The hub will receive the request and transmit it to the entire network.
15. LAN Cable: Local Area Network(LAN) cable is also called as Ethernet or data cable. It is used for connecting a device to the internet.
16. OSI: OSI stands for Open Systems Interconnection. It is a reference model which allows you to specify standards for communications.
17. Unique Identifiers of Network: Below given are some unique network identifiers:
18. Hostname: Every device of the network is associated with a unique device, which is called hostname.
19. IP Address: IP (Internet Protocol) address is as a unique identifier for each device on the Internet. Length of the IP address is 32-bits. IPv6 address is 128 bits.
20. DNS Server: DNS stands for Domain Name System. It is a server which translates URL or web addresses into their corresponding IP addresses.
21. MAC Address: MAC (Media Access Control Address) is known as a physical address is a unique identifier of each host and is associated with the NIC (Network Interface Card). General length of MAC address is : 12-digit/ 6 bytes/ 48 bits
22. Port: Port is a logical channel which allows network users to send or receive data to an application. Every host can have multiple applications running. Each of these applications are identified using the port number on which they are running.
2. Links
Links are the transmission media which can be of two types:
Wired: Examples of wired technologies used in networks include coaxial cables, phone lines, twisted-pair cabling, and optical fibers. Optical fibers carry pulses of light to represent data.
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. Wireless LANs use spectrum technology to establish connections within a small area.
3. Communication protocols
A communication protocol is a set of rules followed by all nodes involved in the information transfer. Some common protocols include the internet protocol suite (TCP/IP), IEEE 802, Ethernet, wireless LAN, and cellular standards. TCP/IP is a conceptual model that standardizes communication in a modern network. It suggests four functional layers of these communication links:
1. Network access layer: This layer defines how the data is physically transferred. It includes how hardware sends data bits through physical wires or fibers.
2. Internet layer: This layer is responsible for packaging the data into understandable packets and allowing it to be sent and received.
3. Transport layer: This layer enables devices to maintain a conversation by ensuring the connection is valid and stable.
4. Application layer: This layer defines how high-level applications can access the network to initiate data transfer.
Most of the modern internet structure is based on the TCP/IP model, though there are still strong influences of the similar but seven-layered open systems interconnection (OSI) model.
IEEE802 is a family of IEEE standards that deals with local area networks (LAN) and metropolitan area networks (MAN). Wireless LAN is the most well-known member of the IEEE 802 family and is more widely known as WLAN or Wi-Fis.
4. Network Defense
While nodes, links, and protocols form the foundation of a network, a modern network cannot exist without its defenses. Security is critical when unprecedented amounts of data are generated, moved, and processed across networks. A few examples of network defense tools include firewall, intrusion detection systems (IDS), intrusion prevention systems (IPS), network access control (NAC), content filters, proxy servers, anti-DDoS devices, and load balancers.
Types of Computer Networks
Computer networks can be classified based on several criteria, such as the transmission medium, the network size, the topology, and organizational intent. Based on a geographical scale, the different types of networks are:
Nanoscale networks: These networks enable communication between minuscule sensors and actuators.
Personal area network (PAN): PAN refers to a network used by just one person to connect multiple devices, such as laptops to scanners, etc.
Local area network (LAN): The local area network connects devices within a limited geographical area, such as schools, hospitals, or office buildings.
Storage area network (SAN): SAN is a dedicated network that facilitates block-level data storage. This is used in storage devices such as disk arrays and tape libraries.
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): MAN is a large computer network that spans across a city.
Wide area network (WAN): Wide area networks cover larger areas such as large cities, states, and even countries.
Enterprise private network (EPN): An enterprise private network is a single network that a large organization uses to connect its multiple office locations.
Virtual private network (VPN): VPN is an overlay private network stretched on top of a public network.
Cloud network: Technically, a cloud network is a WAN whose infrastructure is delivered via cloud services.
Based on organizational intent, networks can be classified as:
Intranet: Intranet is a set of networks that is maintained and controlled by a single entity. It is generally the most secure type of network, with access to authorized users alone. An intranet usually exists behind the router in a local area network.
Internet: The internet (or the internetwork) is a collection of multiple networks connected by routers and layered by networking software. This is a global system that connects governments, researchers, corporates, the public, and individual computer networks.
Extranet: An extranet is similar to the intranet but with connections to particular external networks. It is generally used to share resources with partners, customers, or remote employees.
Darknet: The darknet is an overlay network that runs on the internet and can only be accessed by specialized software. It uses unique, customized communication protocols.
Summary
A computer network is a group of two or more interconnected computer systems Computer networks help you to connect with multiple computers together to send and receive information.
Switches work as a controller which connects computers, printers, and other hardware devices.
Routers help you to connect with multiple networks. It enables you to share a single internet connection and saves money.
Servers are computers that hold shared programs, files, and the network operating system.
Clients are computer device which accesses and uses the network and shares network resources.
Hub is a device that split a network connection into multiple computers.
Access points allow devices to connect to the wireless network without cables.
Network Interface card sends, receives data and controls data flow between the computer and the network.
A protocol is the set of defined rules which that allows two entities to communicate across the network.
Hostname, IP Address, DNS Server, and host are important unique identifiers of computer networks.
ARP stands for Address Resolution Protocol.
RAR Reverse Address Resolution Protocol gives an IP address of the device with given a physical address as input.
Computer network helps you to share expensive software’s and database among network participants.
The biggest drawback of installing computer network is that its initial investment for hardware and software can be costly for initial set-up.