NETWORKING 101 (BASIC CONCEPTS)
Networking, also known as computer networking, is the practice of transporting and exchanging data between nodes over a shared medium in an information system. Networking comprises not only the design, construction and use of a network, but also the management, maintenance and operation of the network infrastructure, software and policies.
With a network, five colleagues can read and edit an evolving document from their own computer with minimal effort and coordination. Without a network, these colleagues have to share time on the same computer or work out a process for exchanging removable storage media. Networks thus, let us all realise economies of scale by running resource-hungry applications on high-power hardware.
WHAT IS A COMPUTER NETWORK?
A network is any interconnected group of people or things capable of sharing meaningful information with one another. In a technology context, “computer/data network” implies that computers are sharing information. All data networks consist of nodes which refers to any computer or digital device using the network and links, the physical connections that carry messages between nodes ( wired/wireless). Data networks are important to all contemporary organisations because they provide faster, easier access to any message or data that can be represented and stored in digital format. In addition to data sharing, computer networks also enable resource sharing, an important consideration in all budget- conscious organisations. Rather than buying one printer for every employee and replacing them every time they wear out, an organisation with a network can buy a single printer, connect it to the network, and configure it in such a way that every computer user in the organisation can print to it.
Apart from networked devices like printers, etc., we can also network and share generic, unspecialised computing power in the form of servers. Servers are large powerful computers that can handle resource-intensive tasks more efficiently than desktop computers.
In the 1980s users with stand-alone computers started to share files using modems to connect to other computers. this was referred to as point-to-point, or dial-up communication. One early solution was the creation of local-area network (LAN) standards. Because LAN standards provided an open set of guidelines for creating network hardware and software, the equipment from different companies could then become compatible.
- 1961 The idea of APRANET, one of the earliest computer networks was proposed by Leonard Kleinrock.
- In 1965, the term ‘packet’ was coined by Donald Davies. The internet was officially born, with the first data transmission being sent between UCLA and SRI on October 29th, 1969 at 10:30pm.
- Eventually Ethernet was developed by Robert Metcalfe in 1973 while working at Xerox PARC.
- In the same year, the first international network connection called SATNET was deployed by ARPA.
- In 1981, Internet Protocol version 4 or IpV4 was officially defined in RFC 791.
- IpV6 was first introduced in 1996 as an improvement over IpV4, including wider range of IP addresses, improved routing and embedded encryption.
- The WPA encryption protocol for WiFi is introduced in 2003.
- The next year, WPA2 encryption is introduced as an improvement over and replacement for WPA.
- All WiFi devices are required to be WPA2 certified by 2006.
- Most recently in 2018, the WiFi Alliance introduced WPA3 encryption in January, which includes security enhancements over WPA2.
Computers in a network are connected in some logical manner, the layout pattern of the interconnections referred to as Network Topology/Architecture. There are a number of different types of network topologies, including point-to- point, bus, star, ring and mesh.
Point-to-point topology is the simplest of all the network topologies. The network consists of a direct link between two computers. This is faster and more reliable than other types of connections since there is a direct connection. The disadvantage is that it can only be used for small areas where computers are in close proximity.
Bus topology uses one main cable to which all nodes are directly connected. The main cable acts as a backbone for the network. One of the computers in the network typically acts as the computer server. The first advantage of bus topology is that it is easy to connect a computer or peripheral device. The second advantage is that the cable requirements are relatively small, resulting in lower cost. One of the disadvantages is that if the main cable breaks, the entire network goes down. This type of network is also difficult to troubleshoot. For these reasons, this type of topology is not used for large networks, such as those covering an entire building.
In star topology, each computer is connected to a central hub using a point-to-point connection. The central hub can be a computer server that manages the network, or it can be a much simpler device that only makes the connections between computers over the network possible.
Star topology is very popular because the startup costs are low. It is also easy to add new nodes to the network. The network is robust in the sense that if one connection between a computer and the hub fails, the other connections remain intact. If the central hub fails, however, the entire network goes down. It also requires more cable than bus topology and is, therefore, more expensive.
In ring topology, the computers in the network are connected in a circular fashion, and the data travels in one direction. Each computer is directly connected to the next computer, forming a single pathway for signals through the network. This type of network is easy to install and manage. If there is a problem in the network, it is easy to pinpoint which connection is defective. It is also good for handling high-volume traffic over long distances since every computer can act as a booster of the signal. On the downside, adding computers to this type of network is more cumbersome, and if one single computer fails, the entire network goes down.
In mesh topology, every node has a direct point-to-point connection to every other node. Because all connections are direct, the network can handle very high-volume traffic. It is also robust because if one connection fails, the others remain intact. Security is also high since data travels along a dedicated connection. Disadvantages are that adding more pc becomes complicated because it is costlier than other topologies. It also needs more NIC ( Network Interface Card ). Mesh topology is mainly implemented in MAN and WAN.
HOW OUR COMPUTERS ACTUALLY COMMUNICATE WITH EACH OTHER
The Open System Interconnection (OSI) model defines a networking framework to implement protocols in seven layers. It is a conceptual framework so we can better understand complex interactions that are happening. The International Standards Organisation (ISO) developed the OSI model. It divides network communication into seven layers. Layers 1-4 are considered the lower layers, and mostly concern themselves with moving data around. Layers 5-7, the upper layers, contain application-level data. Networks operate on one basic principle: “pass it on”. Each layer takes care of a very specific job, and then passes the data onto the next layer. THE 7 LAYERS OF THE OSI In the OSI model, the control is passed from one layer to the next, starting at the application layer ( Layer 7 ), in one station, and proceeding to the bottom layer, over the channel to the next station and back up the hierarchy. The OSI model takes the task of inter-networking and divides that up into what is referred to as a vertical stack that consists of the following 7 layers.
LAYER 7 – APPLICATION
OSI model, layer 7, supports application and end-user processes. Communication parents are identified, quality of service is identified, user authentication and privacy are considered, and any constraints on data syntax are identified. Everything at this layer is application-specific. This layer provides application services for file transfers, e-mail, and other network software services. Telnet and FTP are applications that exist entirely in the application level. Examples of layer 7 application include WWW browsers, Telnet, HTTP, FTP.
LAYER 6 – PRESENTATION
This layer provides independence from differences in data representation (e.g. encryption) by translating from application to network format, and vice versa. The presentation layer works to transform data into the form that the application layer can accept. This layer formats and encrypts data to be sent across a network, providing freedom from compatibility problems. It is sometimes called the syntax layer. Examples of layer 6 presentation include encryption, ASCII, EBCDIC, TIFF, GIF, JPEG, PICT, MPEG, MIDI.
LAYER 5 – SESSION
This layer establishes, manages and terminates connections between applications. The session layer sets up, coordinates, and terminates conversations, exchanges, and dialogues between the applications at each end. It deals with session and connection coordination. Examples of layer 5 session include NFS, NetBios names, RPC, SQL.
LAYER 4 – TRANSPORT
OSI model, layer 4, provides transparent transfer of data between end systems, or hosts, and is responsible for end-to- end error recovery and flow control. It ensures complete data transfer. Examples include SPX,TCP,UDP.
LAYER 3 – NETWORK
Layer 3 provides switching and routing technologies, creating logical paths, known as virtual circuits, for transmitting data from node to node. Routing and forwarding are functions o this layer, as well as addressing, internet working, error handling, congestion control and packet sequencing. Examples include AppleTalk DDP, IP, IPX.
LAYER 2 – DATA LINK
At OSI model, layer 2, data packets are encoded and decoded into bits. It furnishes transmission protocol knowledge and management and handles errors in the physical layer, flow control and frame synchronisation. The data link layer is divided into 2 sub layers – The Media Access Control (MAC) layer and The Logical Link Control (LLC) layer. The MAC sub layer controls how a computer on the network gains access to the data and permission to transmit it. The LLC layer controls frame synchronisation.
LAYER 1 – PHYSICAL
Layer 1 conveys the bit stream – electrical impulse, light or radio signal — through the network at the electrical and mechanical level. It provides the hardware means of sending and receiving data on a carrier, including defining cables, cards and physical aspects. Fast Ethernet, RS232, and ATM are protocols with physical layer components.
Computer Networking lets us access the data from other computers on the same network, and modify it according to our needs. It enables us to share ideas more easily and work more efficiently. It increases productivity and generates more information-based work.
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