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Unformatted text preview: NETWORKING NETWORKING A Network is a system in which nodes are interconnected in such a way that they can share data, hardware and software. A node can be a computer, printer or any other device capable of sending and/or receiving data generated by other nodes on the network. The links connecting the devices are often called communication channels. Types of Networks Types of Networks Networks are referred to following three types: 1.Local Area Network (LAN) 2.Metropolitan Area Network (MAN) 3.Wide Area Network (WAN) LAN LAN A Local Area Network is usually privately owned and links the devices in a single office, building or campus. LAN LAN • One of the computers may be given a large capacity disk drive and may become a server to the other clients. • Software can be stored on this central server and used as needed by the whole group. MAN MAN • A Metropolitan Area Network is designed to extend over an entire city. • It may be a single network such a cable television network so that resources may be shared as device to device WAN WAN • A WAN provides long distance transmission of data, voice, image and video information over large geographic areas that may comprise a country, a continent, or even the whole world. VPN VPN • Generally, used to facilitate mobile users of companies • A specific computer or LAN can be accessed virtually • Secure connection provided by an ISP VAN VAN • Facilities provided through network • Based on EDI Network Architectures Network Architectures There are two basic architectures are used in Networking: 1. Peer to Peer or Point­to­Point 2. Client/Server or Multipoint Peer­to­Peer Peer­to­Peer • A point­to­point connection provides a dedicated link between two devices. • There is no central server • Used in small business, homes etc. Client/Server Client/Server • A client/server connection is one in which individual computers share the processing and storage workload with a central computer • A central computer acts as a server and remaining computers are called clients in the network • It requires special software for the clients and server TOPOLOGY TOPOLOGY The term topology refers to the way in which a network is laid out physically. There are four basic topologies: 1.Mesh Topology 2.Star Topology 3.Bus Topology 4.Ring Topology Mesh Topology Mesh Topology • In a mesh topology, every device has a dedicated point­to­point link to every other device. • A mesh network has n(n­1)/2 physical channels to link n devices. • Every device must have n­1 I/O ports. Mesh Topology Mesh Topology Advantages: Use of dedicated links guarantees that each connection can carry its own data load. Robust or Strong Topology Privacy or Secrecy Easy fault tracing Mesh Topology Mesh Topology Disadvantages: • Expensive Cabling • More I/O ports required • More space required • Star Topology Star Topology In a Star Topology, each device has a dedicated link only to a central controller, usually called a Hub. • The controller acts as an exchange. Star Topology Star Topology Star Topology Star Topology Advantages: Less Expensive than Mesh Easy addition and deletion of devices If one link is failed, only that link is affected Easy fault identification Star Topology Star Topology Disadvantages: • Central Hub is required • More cabling required than Bus or Ring Topology • Bus Topology Bus Topology In Bus Topology, one long cable acts as a backbone to link all the devices in a network. • Nodes are connected to the bus cable by drop lines and taps. • 12­15 computers can be added with the bus. Bus Topology Bus Topology Bus Topology Bus Topology Advantages: Easy installation Easy addition & deletion of nodes Less cabling is required (Only backbone cables is the main expense) Bus Topology Bus Topology Disadvantages: • Fault tracing is difficult • Fault or break in backbone cable stops all transmission • Supports only small number of nodes • Ring Topology Ring Topology In a Ring Topology, each device has a dedicated connection with two adjacent sides • The message travels to each node until it reaches the destination Ring Topology Ring Topology Ring Topology Ring Topology Advantages: Easy to install & Reconfigure To add or delete a device requires changing only two connections Less expensive than star or mesh Alarm Alert in case of fault Ring Topology Ring Topology Disadvantages: • Break in ring can disable the whole network • Two I/O devices required for each computer Data Communication Protocol Data Communication Protocol • A protocol is a set of rules that governs how information is delivered from one place to other • Here are some important data communication protocols: – Ethernet – Token Ring – TCP/IP –WAP Ethernet Protocol Ethernet Protocol • Used over Local Area Network •Uses cables for data transmission • Based on Bus and Star topologies Token Ring Protocol Token Ring Protocol • Used over Local Area Network • A special signal called Token is used to access any computer in network • No collision • Based on Ring topology TCP/IP TCP/IP • Abbreviation of Transmission Control Protocol/Internet Protocol • Used over Internet • Data is divided into Packets • Every Packet contains addresses of source and destination computers WAP WAP • Abbreviation of Wireless Application Protocol • Used in mobile computing • Based on Client/Server architecture Switch Switch • Switch works like a Hub • An intelligent device. Unlike, Hub, the message is not broadcasted • More expensive than hub Router Router • Router is used for sending data from a particular station of a LAN to remote station of another LAN. • It chooses best shortest path for data transfer. Router Router • Acts as Store­and­forward message relay system • Protocol of all the LANs should be same Modem Modem • Modulator – DEModulator • Used to send and receive signal through telephone lines ...
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