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.
LAN (LOCAL AREA NETWORK) WAN (WIDE AREA NETWORK) MAN (METROPOLITAN AREA NETWORK) PAN (PERSONAL AREA NETWORK) VPN (VIRTUAL PRIVATE NETWORK) CAN (CAMPUS AREA NETWORK) GAN(GLOBAL AREA NETWORK) SAN (STORAGE AREA NETWORK)
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.
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.
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.
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.
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.
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
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 TopologyEasy to connect a computer or peripheral to a linear bus.Requires less cable length than a star topology.Disadvantages of a Linear Bus TopologyEntire network shuts down if there is a break in the main cable.Terminators are required at both ends of the backbone cable.
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 TopologyEasy to install and wire.No disruptions to the network then connecting or removing devices.Disadvantages of a Star TopologyRequires more cable length than a linear topology.If the hub or concentrator fails, nodes attached are disabled.
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 TopologyGrowth 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 TopologyMost expensive topology.Failure of one computer may impact others .Complex .
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 TopologySystem provides increased redundancy and reliability as well as ease oftroubleshooting.Data transfer is faster.Disadvantages of a Mesh TopologySystem is expensive to install because it uses a lot of cabling.
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 TopologyPoint-to-point wiring for individual segments.The network doesn`t fail even when a link between two nodes is broken.Disadvantages of a Tree TopologyOverall length of each segment is limited by the type of cabling used.If the backbone line breaks, the entire segment goes down.
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
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.
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 .
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.
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.
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 .
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.
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.
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.
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