Digital Planet: Tomorrow’s Technology and You Chapter 8 Networking and Digital Communication Copyright © 2012 Pearson Education, Inc. publishing as Prentice Hall

Basic Network Anatomy A computer network is any system of two or more computers that are linked together. Three essential components of every computer system: Hardware Software People 2

Copyright © 2012 Pearson Education, Inc. publishing as Prentice Hall Networks Near and Far LAN (local area network): computers are physically close to each other Nodes: connected to hubs or switches, which allow any node on the network to communicate with any other WAN (wide area network): extends over a long distance Each networked LAN site is a node on the WAN Ethernet: popular networking architecture developed in the 1970s; now an industry standard 3

Copyright © 2012 Pearson Education, Inc. publishing as Prentice Hall The Importance of Bandwidth Bandwidth: refers to the quantity of data that can be transmitted through a communication medium in a given amount of time Typically measured in kilobits or megabits per second Bandwidth can be affected by: Physical media of the network Amount of traffic on the network Type of network connection Collisions and retries 4

Copyright © 2012 Pearson Education, Inc. publishing as Prentice Hall Communication Software Protocol: set of rules for the exchange of data between devices Computers must follow the same protocols to understand each other. TCP/IP: most famous protocol for computer networking TCP/IP controls the exchange of data. 5

Copyright © 2012 Pearson Education, Inc. publishing as Prentice Hall TCP/IP As with all other communications protocol, TCP/IP is composed of layers: IP - is responsible for moving packet of data from node to node. IP forwards each packet based on a four byte destination address (the IP number). TCP - is responsible for verifying the correct delivery of data from client to server. Data can be lost in the intermediate network. TCP adds support to detect errors or lost data and to trigger retransmission until the data is correctly and completely received. 6

Copyright © 2012 Pearson Education, Inc. publishing as Prentice Hall TCP/IP TCP/IP assigns a unique number to every computer in the world. This "IP number" is a four byte value that, by convention, is expressed by converting each byte into a decimal number (0 to 255) and separating the bytes with a period. For example, the Sage.edu server might be

Copyright © 2012 Pearson Education, Inc. publishing as Prentice Hall TCP/IP TCP treats the data as a stream of bytes. It logically assigns a sequence number to each byte. The TCP packet has a header that says, in effect, "This packet starts with byte and contains 200 bytes of data." The receiver can detect missing or incorrectly sequenced packets. TCP acknowledges data that has been received and retransmits data that has been lost. These packets are not delivered in all together, but separately and via various routes. 8

Copyright © 2012 Pearson Education, Inc. publishing as Prentice Hall Wi-Fi and WiMax Technology (cont.) WiMAX: new radio-based wireless standard in which a single tower can provide access to a 25-square-mile area WEP (wired equivalent privacy): encryption scheme improves the security of wireless networks VPN (virtual private network): electronic "tunnel” through the Internet that helps to prevent eavesdropping 9

Copyright © 2012 Pearson Education, Inc. publishing as Prentice Hall Bluetooth Technology Bluetooth technology: named for Danish king who overcame his country’s religious differences Overcomes differences between mobile phones, handheld computers, and PCs, allowing communication between different operating systems. 10

Copyright © 2012 Pearson Education, Inc. publishing as Prentice Hall Sharing Resources: Peer-to-Peer, Grid, and Cloud Computing Peer-to-peer: file sharing allows users to share files by making their hard drives available to other users rather than posting them on a central server Cloud computing: form of grid computing where the resources come from the Internet rather than a specific source 11