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7/28/2016 Objectives Overview Discovering Computers Technology in a World of Computers, Mobile Devices, and the Internet Chapter 10 Communications and Networks Objectives Overview Describe various types of communications lines See Page 416 for Detailed Objectives Differentiate among LANs, MANs, WANs, and PANs Differentiate between client/server and peer-topeer networks Differentiate among a star network, bus network, and ring network Describe the various network communications standards
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  7/28/20161 Chapter 10 Communications and Networks Discovering Computers Technology in a World of Computers, Mobile Devices, and the Internet Objectives Overview Discuss the purpose of the components required for successful communications and identify various sending and receiving devicesDifferentiate among LANs, MANs, WANs, and PANsDifferentiate between client/server and peer-to-peer networksDifferentiate among a star network, bus network, and ring networkDescribe the various network communications standards and protocolsExplain the purpose of communications software Discovering Computers 2014: Chapter 10 2 See Page 416for Detailed Objectives Objectives Overview Describe various types of communications linesDescribe commonly used communications devicesDiscuss different ways to set up and configure a home networkDifferentiate among physical transmission mediaDifferentiate among wireless transmission media Discovering Computers 2014: Chapter 10 3 See Page 416for Detailed Objectives Communications ã Digital communicationsdescribes a process in which two or more computers or devices transfer data, instructions, and information Discovering Computers 2014: Chapter 10 4 Page 416   Sending deviceCommunications channelReceiving device  7/28/20162 Communications Discovering Computers 2014: Chapter 10 5 Page 417Figure 10-1 Networks ã A network is a collection of computers and devices connected together via communications devices and transmission media ã Advantages of a network include: Discovering Computers 2014: Chapter 10 6 Pages 418 -419 Facilitating communicationsSharing hardwareSharing data and informationSharing softwareTransferring funds Networks 7 Networks ã A local area network ( LAN ) is a network that connects computers and devices in a limited geographical area ã A wireless LAN ( WLAN ) is a LAN that uses no physical wires 8  7/28/20163 Networks ã A metropolitan area network ( MAN ) connects LANs in a metropolitan area ã A wide area network ( WAN ) is a network that covers a large geographic area ã A personal area network ( PAN ) is a network thatconnects computers and devices in an individual’s workspace with wired andwireless technology 9   Networks ã The configuration of computers, devices, and media on a network is sometimes called the network architecture 10 Client/server networkPeer-to-peer network P2P network is simple, inexpensive network architecture that typically connects fewer than 10 computers. Each computer or mobile device, called a peer, has equal responsibilities and capabilities, sharing hardware (such as a printer), data or information with other computers and mobile devices on the p2p network.One or more computers act as a server, and the other computers on the network request services from the server. A server, sometimes called a host computer, controls access to the hardware, software, and other resources on the network and provides a centralized storage area for programs, data, and information. Networks ã A network topology refers to the layout of the computers and devices in a communications network Discovering Computers 2014: Chapter 10 11 Pages 423  – 424Figures 10-8  – 10-10 Star networkBus networkRing network 12 Network Communications Standards and Protocols STAR Topology in this type of topology all the computers are connected to a single hub through a cable. This hub is the central node and all others nodes are connected to the central node. 12 Features of Star Topology 1.Every node has its own dedicated connection to the hub.2.Hub acts as a repeater for data flow.3.Can be used with twisted pair, Optical Fiber or coaxial cable. Advantages of Star Topology 1.Fast performance with few nodes and low network traffic.2.Hub can be upgraded easily.3.Easy to troubleshoot.4.Easy to setup and modify.5.Only that node is affected which has failed, rest of the nodes can work smoothly. Disadvantages of Star Topology 1.Cost of installation is high.2.Expensive to use.3.If the hub fails then the whole network is stopped because all the nodes depend on the hub.4.Performance is based on the hub that is it depends on its capacity  7/28/20164 13 Network Communications Standards and Protocols BUS Topology is a network type in which every computer and network device is connected to single cable. When it has exactly two endpoints, then it is called Linear Bus topology. 13 Features of Bus Topology 1.It transmits data only in one direction.2.Every device is connected to a single cable Advantages of Bus Topology 1.It is cost effective.2.Cable required is least compared to other network topology.3.Used in small networks.4.It is easy to understand.5.Easy to expand joining two cables together. Disadvantages of Bus Topology 1.Cables fails then whole network fails.2.If network traffic is heavy or nodes are more the performance of the network decreases.3.Cable has a limited length.4.It is slower than the ring topology. Network Communications Standards and Protocols RING Topology it is called ring topology because it forms a ring as each computer is connected to another computer, with the last one connected to the first. Exactly two neighbors for each device. 14 Features of Ring Topology 1.A number of repeaters are used for Ring topology with large number of nodes, because if someone wants to send some data to the last node in the ring topology with 100 nodes, then the data will have to pass through 99 nodes to reach the 100th node. Hence to prevent data loss repeaters are used in the network.2.The transmission is unidirectional, but it can be made bidirectional by having 2 connections between each Network Node, it is called Dual Ring Topology. In Dual Ring Topology, two ring networks are formed, and data flow is in opposite direction in them. Also, if one ring fails, the second ring can act as a backup, to keep the network up.3.Data is transferred in a sequential manner that is bit by bit. Data transmitted, has to pass through each node of the network, till the destination node. Network Communications Standards and Protocols RING Topology it is called ring topology because it forms a ring as each computer is connected to another computer, with the last one connected to the first. Exactly two neighbors for each device. Discovering Computers 2014: Chapter 10 15 Pages 425 -426 Advantages of Ring Topology 1. Transmitting network is not affected by high traffic or by adding more nodes, as only the nodes having tokens can transmit data.2. Cheap to install and expand Disadvantages of Ring Topology 1. Troubleshooting is difficult in ring topology.2. Adding or deleting the computers disturbs the network activity.3. Failure of one computer disturbs the whole network. Network Communications Standards and Protocols A network standard defines guidelines that specify the way computers access the medium to which they are connected, the type(s) of medium used, the speeds used on different types of networks, and the type(s) of physical cable and/or the wireless technology used. Hardware and software manufacturers design their products to meet the guidelines specified in a particular standard  , so that their devices can communicate with the network.A standard  that outlines characteristics of how two devices communicate on a network is called a  protocol  . Specifically, a protocol may define data format, coding schemes, error handling, and the sequence in which data transfers over a network. Discovering Computers 2014: Chapter 10 16 Pages 425 -426 ã To alleviate the problems of incompatibility and ensure that hardware and software components can be integrated into any network, various organizations such as ANSI (American National Standards Institute) and IEEE (Institute of Electrical and Electronics Engineers) propose, develop, and approve network standards.
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