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  • 2. INTRODUCTION-What is networking? A network is a collection of computers and devices connected to each other. Thenetwork allows computers to communicate with each other and share resources andinformation.In other words networking can be defined as inter-connection of two or morecomputers for sharing the resources(hardware and software)and provide security onthem. Networks are built with a combination of computer hardware and computersoftware.
  • 4.  Local area networks (LANs) are computer networks ranging in size from afew computers in a single office to hundreds or even thousands of devicesspread across several buildings. LANs in turn may be plugged into larger networks, such as larger LANs orwide area networks (WANs), connecting many computers within anorganization to each other and/or to the Internet. Typically, connected devices share the resources of a single processor orserver within a small geographic area (for example, within an office building). Usually, the server has applications and data storage that are shared incommon by multiple computer users.
  • 5.  A wide area network (WAN) is a computer network that covers a broad area(i.e. any network whose communications links cross metropolitan, regional, ornational boundaries). WAN is a network that uses routers and public communications links. The largest and most well-known example of a WAN is the Internet. A WANis a data communications network that covers a relatively broad geographicarea (i.e. one city to another and one country to another country) and that oftenuses transmission facilities provided by common carriers, such as telephonecompanies. WAN technologies generally function at the lower three layers of the OSIreference model: the physical layer, the data link layer, and the network layer.
  • 6.  A metropolitan area network (MAN) is a network that connects two or morelocal area networks or campus area networks together but does not extendbeyond the boundaries of the immediate town/city. Routers, switches and hubs are connected to create a metropolitan areanetwork. The term is applied to the interconnection of networks in a city into a singlelarger network (which may then also offer efficient connection to a wide areanetwork). It is also used to mean the interconnection of several local area networks bybridging them with backbone lines.
  • 7.  A personal area network (PAN) is a computer network used forcommunication among computer devices close to one person. Examples of devices that are used in a PAN are :printers, faxmachines, telephones, PDAs and scanners. The reach of a PAN is typically about 20-30 feet approximately 6-9 meters.GLOBAL AREANETWORK(GAN) A global area networks (GAN) specification is in development by severalgroups, and there is no common definition. In general, however, a GAN is a model for supporting mobile communicationsacross an arbitrary number of wireless LANs, satellite coverage areas, etc.
  • 8.  A virtual private network (VPN) is a computer network in which some of thelinks between nodes are carried by open connections or virtual circuits insome larger network (e.g., the Internet) instead of by physical wires. A VPN may have best-effort performance, or may have a defined service levelagreement (SLA) between the VPN customer and the VPN service provider.Generally, a VPN has a topology more complex than point-to-point. A VPN allows computer users to appear to be editing from an IP addresslocation other than the one which connects the actual computer to the Internet.CAMPUSAREANETWORK(CAN) A campus area network (CAN) is a computer network made up of aninterconnection of local area networks (LANs) within a limited geographicalarea. It can be considered one form of a metropolitan area network, specific to anacademic setting.
  • 9.  A network consists of two or more computers that are linked in order to shareresources (such as printers and CD-ROMs), exchange files, or allow electroniccommunications. The computers on a network may be linked through cables, telephonelines, radio waves, satellites, or infrared light beams.TYPES BUS TOPOLOGY STAR TOPOLOGY RING TOPOLOGY MESH TOPOLOGY STAR BUS TOPOLOGY TREE OR HIERARCHICAL
  • 10. A linear bus topology consists of a main run of cable with a terminator a eachend. All nodes (file server, workstations, and peripherals) are connected to thelinear cable. Ethernet and Local Talk networks use a linear bus topology.Linear bus structureAdvantages of a Linear Bus TopologyEasy to connect a computer or peripheral to a linear bus.Requires less cable length than a star topology.Disadvantages of a Linear Bus TopologyEntire network shuts down if there is a break in the main cable.Terminators are required at both ends of the backbone cable.
  • 11.  A star topology is designed with each node (file server, workstations, andperipherals) connected directly to a central network hub or concentrator. Data on a star network passes through the hub or concentrator beforecontinuing to its destination. The hub or concentrator manages and controls allfunctions of the network.star structureAdvantages of a Star TopologyEasy to install and wire.No disruptions to the network then connecting or removing devices.Disadvantages of a Star TopologyRequires more cable length than a linear topology.If the hub or concentrator fails, nodes attached are disabled.
  • 12.  The ring topology is a type of computer network configuration where eachnetwork computer and device are connect to each other forming a large circle. Each packet is sent around the ring until it reaches its final destination.Ring structureAdvantages of a Ring TopologyGrowth of system has minimal impact on performance.All stations have equal access.The network doesn`t fail even when a link between two nodes is broken.Disadvantages of a Ring TopologyMost expensive topology.Failure of one computer may impact others .Complex .
  • 13.  It requires that every terminal should be attached to each other. All the computers must have adequate number of interfaces for theconnections to be made. Because of this requirement the installations issomewhat difficult. The length of cable required is quite higher as compared to other topologies.Mesh structureAdvantages of a Mesh TopologySystem provides increased redundancy and reliability as well as ease oftroubleshooting.Data transfer is faster.Disadvantages of a Mesh TopologySystem is expensive to install because it uses a lot of cabling.
  • 14.  A tree topology combines characteristics of linear bus and star topologies. It consists of groups of star-configured workstations connected to a linear busbackbone cable. Tree topologies allow for the expansion of an existing network, and enableschools to configure a network to meet their needs .Tree structureAdvantages of a Tree TopologyPoint-to-point wiring for individual segments.The network doesn`t fail even when a link between two nodes is broken.Disadvantages of a Tree TopologyOverall length of each segment is limited by the type of cabling used.If the backbone line breaks, the entire segment goes down.
  • 15.  All networks are made up of basic hardware building blocks to interconnectnetwork nodes, such as Network Interface Cards(NICs), Bridges, Hubs, Switches, and Routers. In addition, some method of connecting these building blocks isrequired, usually in the form of galvanic cable . Less common are microwave links or optical cable (“optical fibre"). AnEthernet card may also be required.Some of the basic components required for interconnecting the networknodes: NETWORK INTERFACE CARD REPEATERS NETWORK HUB NETWORK BRIDGE NETWORK SWITCH ROUTER
  • 16.  A network card, network adapter or NIC (network interface card) is a piece ofcomputer hardware designed to allow computers to communicate over acomputer network. It provides physical access to a networking medium and often provides a low-level addressing system through the use of MAC addresses.REPEATER A repeater is an electronic device that receives a signal and retransmits it at ahigher power level, or to the other side of an obstruction, so that the signal cancover longer distances without degradation. In most twisted pair Ethernet configurations, repeaters are required for cableruns longer than 100 meters.
  • 17.  A hub contains multiple ports. When a packet arrives at one port, it is copied unmodified to all ports of thehub for transmission. The destination address in the frame is not changed to a broadcast address.ROUTER Routers are networking devices that forward data packets between networksusing headers and forwarding tables to determine the best path to forward thepackets. Routers work at the network layer .
  • 18.  A network bridge connects multiple network segments at the data link layer(layer 2) of the OSI model. Bridges do not promiscuously copy traffic to all ports, as hubs do, but learnwhich MAC addresses are reachable through specific ports. Once the bridge associates a port and an address, it will send traffic for thataddress only to that port. Bridges do send broadcasts to all ports except the one on which the broadcastwas received.Bridges come in three basic types: Local bridges: Directly connect local area networks (LANs). Remote bridges: Can be used to create a wide area network (WAN) linkbetween LANs. Remote bridges, where the connecting link is slower than theend networks, largely have been replaced by routers. Wireless bridges: Can be used to join LANs or connect remote stations toLANs.
  • 19.  A switch is a device that forwards and filters OSI layer 2 datagrams betweenports based on the MAC addresses in the packets. This is distinct from a hubin that it only forwards the packets to the ports involved in thecommunications rather than all ports connected. Strictly speaking, a switch is not capable of routing traffic based on IP addresswhich is necessary for communicating between network segments or within alarge or complex LAN. A switch normally has numerous ports, with the intention being that most orall of the network is connected directly to the switch, or another switch that isin turn connected to a switch. Switch is a marketing term that encompassesrouters and bridges, as well as devices that may distribute traffic on load or byapplication content. Switches may operate at one or more OSI model layers, includingphysical, data link, network, or transport (i.e., end-to-end). A device thatoperates simultaneously at more than one of these layers is called a multilayerswitch.
  • 20. The main reasons are: Distribute pieces of computation among computers (nodes) . Coordination between processes running on different nodes . Remote I/O Devices . Remote Data/File Access . Personal communications (like e-mail, chat, audio/video conferencing). World Wide Web .
  • 21. Performance parameters: Latency: Time required to transfer an empty message between relevantcomputers.Sum total of delay introduced by the sender software. delay introduced by the receiver software. delay in accessing the network. delay introduced by the network. Data transfer rate: is the speed at which data can be transferred betweensender and receiver in a network, once transmission has begun. (bit/sec) . Message transfer time = latency + (length of message) / (Data transfer rate). Bandwidth: is the total volume of traffic that can be transferred across thenetwork. Max. data rate (bit/sec) = carrier BW · log2 (1 + (signal/noise)) .Thismaximum (Shannons Limit) is theoretical, not reachable in practice. Ex: phone line BW = 3 kHz, S/N = 30 dB = 1000 Max. data rate = 30 kbit/sec.
  • 22. Coaxial cableTwisted pair cableOptical fibreWireless
  • 23.  Developed at Xerox PARC in 1973. Its a standard for Media Access Control (MAC) sub layer. Data transmission rate : 10 Mbits/s (Fast Ethernet reaches 100 Mbit/s). High-speed driver on the computers connected by coax or UTP cables. Uses a bus (10base2, coax, max. distance 200 mts) or a star(10baseT, UTP, max. 100 mts) topology. Can be optical fibres based too (10baseF , max. 2000 mts).How it works? All nodes wanting to send message contention for the bus. Broadcast frames to all the stations on the network. All stations are continually listening to the bus looking for frames addressed tothem . Variable length frames:64 to 1518 bytes. Transmission time : 50 to 1200.
  • 24.  Its a 32 bits, 4-part period delimited, decimal number called IP number or IPaddress:www.xxx.yyy.zzz Each part can vary from 1 to 254 (0 and 255 are reserved for the net and thebroadcast). Each network interface card attached to the Internet mast have an unique IPaddress. The IP address can be splitted in two parts: Network. Host.
  • 25. Sub netting allow a network to be split into several parts for internaluse but still act like a single one to the outside world.Allocation of Network andhostAllocation of Network ,hostand sub net
  • 26. Done by,B.PrashanthR.Vignesh