Computer Network and Internet

Network and Internet

Computer Network : A computer network is a set of connected computers. Computers on a network are called nodes. The connection between computers can be done via cabling, most commonly the Ethernet cable, or wirelessly through radio waves. Connected computers can share resources, like access to the Internet, printers, file servers, and others.

  • Server – A computer designed to process requests and deliver data to other (client) computers over a local network or the Internet.
  • Receiver – a hardware module or device used to receive signals.
  • Channel – physical connection between Server & Receiver.

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Network Channel

Simplex channels – simplex is a communications channel that operates in one direction at a time. Example: Keyboard and traditional monitors.

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Half duplex channel A half-duplex channel can send and receive data, but not at the same time. Example: Walkie- talkie

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Full duplex channel – Refers to the transmission of data in two directions simultaneously.

Example: Telephone Network

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Network devices

i)Network adapter is a device that enables a computer to connect with other computer/network using MAC Address

ii) Hub is a device that splits a network connection into multiple computers

iii) Switch is a telecommunication device grouped as one of computer network components

iv) Cable is one way of transmission media which can transmit communication signals.

v) Repeaters is used to regenerate or replicate signals that are weakened or distorted by transmission over long distances

vi) Bridge is used two connect two LANs with the same standard but using different types of cables

vii) Routers is used to join multiple computer networks together via either wired or wireless connections.

viii) Gateways is a key stopping point for data on its way to or from other networks.

ix) MODEM – Modulator-demodulator. Electronic device that allows computers to communicate over telephone wires or cable-TV cable.

Types of Network

  • Local Area Netwok(LAN) – a computer network that links devices within a building or group of adjacent buildings.Ex – Star LAN, Ring LAN, Bus LAN
  • Wide Area Network(WAN) – a computer network in which the computers connected may be far apart.
  • Metropolitan Area Network (MAN)- A metropolitan area network (MAN) is a network that interconnects users with computer resources in a geographic area or region larger than that covered by even a LAN but smaller than the area covered by WAN. Ex- Public Networks Public Switched Telephone Networks (PSTN) Public Service Digital Network (PSDN)
  • Integrated Services Digital Network (ISDN) is a set of communication standards for simultaneous digital transmission of voice, video, data

Network Topology:

  • Mesh topology – Mesh is a network topology in which devices are connected with many redundant interconnections between network nodes.
  • Star topology – Star topology is a network topology where each individual piece of a network is attached to a central node.
  • Ring topology – Ring topology refers to a specific kind of network setup in which devices are connected in a ring and pass information to each other according to their adjacent in the ring structure.
  • Bus topology – Bus topology is a specific kind of network topology in which all of the various devices in the network are connected to a single cable or line.
  • Tree toplogy – It is a combination characteristics of linear bus and star topologies.

OSI MODEL

OSI : The Open Systems Interconnection model (OSI Model) is a conceptual model that characterizes and standardizes the communication functions of a telecommunication or computing system without regard of their underlying internal structure and technology.

Seven layers of OSI Model

1.Physical layer – The physical layer is the first layer of the OSI Model that deals with bit-level transmission between different devices and supports electrical or mechanical interfaces connecting to the physical medium for synchronized communication.

2.Data Link Layer – The data link layer is the second layer of OSI model.This layer is the protocol layer that transfers data in the form of frames between adjacent network nodes in a wide area network or between nodes on the same local area network segment.

3.Network Layer – The network layer is the third level of the OSI Model and the layer that provides data routing paths for network communication. Data is transferred in the form of packets via logical network paths in an ordered format controlled by the network layer.

4.Transport Layer – The transport layer is the layer in the OSI model responsible for end-to-end communication(in the form of segments) over a network. It provides logical communication between application processes running on different hosts within a layered architecture of protocols and other network components.

5.Session Layer – In the OSI model, the session layer is the fifth layer, which controls the connections between multiple computers. The session layer tracks the dialogs between computers, which are also called sessions.

6.Presentation Layer – The presentation layer is layer 6 in OSI model. It is used to present data to the application layer (layer 7) in an accurate, well-defined and standardized format. The presentation layer is sometimes called the syntax layer.

7.Application Layer – The application layer is a layer in the OSI model and in the TCP/IP protocol suite. It consists of protocols that focus on process-to-process communication across an IP network and provides a firm communication interface and end-user services.

Data transmission

  • NIC-Network interface card – A network interface card (NIC) is a computer circuit board or card that is installed in a computer so that it can be connected to a network.
  • Wireless technology – Wireless communications is a type of data , a wireless signal through wireless communication technologies and device.

Network Related Terms

i)Protocol – It is set of rules and standards which is used by computers to exchange data or information with each other across a network.

ii) Nodes – It is a connect point where either data transmission ends or redistribution of data starts.

iii) TCP/IP (Transmission Control Protocol/Internet Protocol) – basic communication language or protocol of the Internet.

IPV4 – 32 bits numeric address IPV6 – 128 bits hexadecimal address

iv) File Transfer Protocol (FTP) is a standard network protocol used to transfer computer files between a client and server on a computer network.

v) Internet service provider (ISP) is an organization that provides services for accessing and using the Internet.

vi) Network Service Provider (NSP) is a company that provides backbone services to an Internet service provider (ISP).

vii) Web server is a program that uses HTTP (Hypertext Transfer Protocol) to serve the files that form Web pages to users, in response to their requests, which are forwarded by their computers’ HTTP clients.

viii) Website is a collection of related web pages, including multimedia content, typically identified with a common domain name

ix) Web Page is a hypertext document connected to the World Wide Web.

x) Home page – the introductory page of a website

xi) Hyperlink is a word, phrase, or image that you can click on to jump to a new document or a new section within the current document.

Xii) Hypertext Transfer Protocol (HTTP) is an application protocol for distributed, collaborative, hypermedia information systems.

xiii) Wireless Application Protocol (WAP) is a technical standard for accessing information over a mobile wireless network.

URL (Uniform Resource Locator) is a form of URI and is a standardized naming convention for addressing documents accessible over the Internet and Intranet.

Internet

  • Internet- a global computer network providing a variety of information and communication facilities, consisting of interconnected networks using standardized communication protocols.
  • Modem – a combined device for modulation and demodulation, for example, between the digital data of a computer and the analogue signal of a telephone line.
  • Web Browser – Web browser is a software application used to locate, retrieve and display content on the World Wide Web, including Web pages, images and video.

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