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IB Computer Science - Topic 3 -
Networks
bus topology Computer network in which a "bus" connects all the devices together through a common cable check digit Extra digit added to numerical data that is used to check data integrity after input, transmission, storage and processing. data integrity The accuracy of data after input, transmission, storage or processing check sum Error-detecting procedure that generates a sum from the digits of a number. data packet Portion of a message that is transmitted through a network. Contains data such as check digits and destination address. gateway Link that resides between computer networks and is responsible for converting data passing through the appropriate format so it can be understood by the received network handshaking Exchange of predetermined signals to signify that a connection has been established between two systems. hub Network connection point for devices. Data arriving at a hub is copied and sent to all the devices on the network. cable Copper wire (usually coaxial and twisted pair) and fibre (fibre cable-made from glass). Cables allow for the connection of computers over a network.
ISDN Integrated Services Digital Network - International communications standard that allows for the transmission of audio/video and other data over digital telephone lines. LAN Computer network where all the connected computers are within a limited geographical area (e.g. a home, school etc); connection between the computers may be through cables and/or microwave transmission microwave transmission Electronic communication without the need for cables. modem Equipment that converts computer digital signals into audio signals and back. Audio signals are transmitted over telephone lines, allows distant communication. network Computer systems that are interconnected and can share resources and data. packet Group of bits. May include control signals, error control bits, coded information, as well as the destination for the data. packet switching Network communication method and transmits small units of data, called packets, through a network, independently of the overall message parity bit Error-detecting procedure that appends a binary digit to a group of binary digits. The sum of all the digits, including the appended binary digit, establishes the accuracy of the data after input, transmission, storage or processing. protocol International rules that ensure the transfer of data between systems. Standard protocol is protocol that is recognized as the standard for a specific form of communication. WAN Computer network where all the connected computers are in a larger geographic area than that served by a LAN (metropolitan area network).
server In computing, a server is a computer program or a device that provides functionality for other programs or devices, called "clients". switch A switch is used to network multiple computers together. Switches made for the consumer market are typically small, flat boxes with 4 to 8 Ethernet ports. These ports can connect to computers, cable or DSL modems, and other switches. High-end switches can have more than 50 ports and often are rack mounted. router Networking device that joins multiple computer networks and serves as in intermediary between these networks so data can be exchanged efficiently and effectively between these devices internet of things the interconnection via the Internet of computing devices embedded in everyday objects, enabling them to send and receive data. Broadband High capacity transmission technique that uses a wide range of frequency, allows multiple messages to be communicated simultaneously 3G/4G Standards for wireless mobile connectivity allowing access from mobile devices to the internet. Dial up access via modem. Used where broadband access is not available or too expensive, or no Wi-Fi available. VPN Makes a "tunnelled" network connection through the internet or any other public network, considered ideal for establishing a secure connection between private networks with remote users and remote sights standards Describe the common ground on which hardware and software manufacturers can depend on in order to build systems that are able to communicate with each other.
They can be thought to provide a common international "language" that enables compatibility for all computer systems throughout the globe. Why are Network communication layers needed? It is to reduce complexity, so that each component of hardware and software only need to perform a single function. OSI The Open Systems Interconnection model is a way of standardising data transmission to simplify the complex requirements into seven abstract "layers". Physical Layer (OSI) Transmits 0s and 1s over media between devices. Definition of media specification. Voltage levels. Example protocol: RS232-C (serial port). Data Link Layer (OSI) Error handling of physical transmission, builds frames and amends transmission rate according the buffer of the receiver Network Layer (OSI) This layer is responsible for packet forwarding including routing through intermediate routers, since it knows the address of neighbouring network nodes, and it also manages quality of service (QoS), and recognises and forwards local host domain messages to the transport layer. Transport Layer (OSI) End to end connections. Definition of data segments, assignment of numbers, data transfer, reassemblage of data at the destination. Breaks down file, assigns number to each segment, transfers data, reassembles file at destination. Session Layer (OSI) This layer provides the mechanism for opening, closing and managing a semi- permanent dialogue between end-user application processes. Presentation Layer (OSI) Provides data format information, data compression information and data encryption information to the application. Example protocol: Portable Network Graphics (PNG). Application Layer (OSI) Performs various services for the application used by the end users
Feeling stressed, have to be available all the time Not all devices can connect wirelessly Wifi 3G WiMAX A 4G network originally designedd as an alternative to DSL Cable and T1 lines. Intended to provide 30 to 40 mbps data rates for a great number of users. Wireless Network Hardware Requirements Wireless Network Software Requirements
