networking word file

8/7/2019 networking word file

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PROJECT ON COMPUTER NETWORKING AND TYPES

MADE BY- CLINTON VAZ (47)

VINAY VERMA (48),

VIVEK VERMA (49),

Y.JITENDRA (50).


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Srno Contents

01 Introduction

02 Uses

03 Advantages and Disadvantages ofComputerNetworks

04 Importance of ComputerNetworking

05 Types of networking

06 Network topology

07 Classification of Networking

08 Network Cables and Cabling

09 Slides


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INTRODUCTION

What is Networking?

Networking means connectionof computers toeach otherwhich

are capable for sharing resources and different application.

Information canbesharedbetween computers usingtransmission

media. Networkingis the practice of linking two or more

computingdevices together for the purposeofsharingdatabuilt

with a mix of computer hardware and computer software. The

purposeofanetworkistoshareresources. Theaim ofcomputernetworksisnotonlytoexchangedatabutalsoto understandand

usethedatareceivedfrom entitiesnetwork.

Networkingallows toshare hardwaresuch as printers , scanner,

telephone,ets. Same information can be shared between

computers in a same organization. Data can be transferred in

electronic manner through network. Network distributes

messages by storing them in an appropriate box. Usingnetworking user can store data on a single machine called as

server towhich all computersare connected. Also user build

decentralizednetworkthat meanseach otherandevery computer

canstoredataandsharedata. Network canbebuildas peruser

requirement.


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Uses of computernetworks

Uses of Networks forCompanies

Ifyourbusiness has more thanone computer, chancesareyoucouldbenefit from networking them. A localareanetwork (LAN)connectsyourcompany's computers, allowingthem toshareandexchange a variety of information. While one computer can beusefulonitsown, severalnetworked computers can

Theyareasfollows

Resource Sharing:Manyorganizations have largenumberofsubstantial computersinoperationoftenlocatedfarapart. Let us consideranexample, acompany having many factories situated at different locations.A computerat each location (that is in each factory) keeps thetrackofinventories, monitorproductivityanddothelocal payroll.


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Initially each of these computers may haveworked in isolationfrom each other, butatsome point, the management may havedecided to connect these computers to be able to extract andcorrelate the information of the entire company.

The issue here is resource sharing. Its goal is to make all theprograms, equipments, especially data available to anyone onthenetworkirrespective of the location of the resource and theuser.

High Reliability:

The second goal or use of networking in companiesis to highreliabilityby havingalternativesourcesofsupply. Forexampleallthe files canbe replicatedon twoor more machines, so that incaseoneofthem isnotavailable (dueto hardwarefailure), othercopies canbe used. This feature is used in financial institutions.

Saving Money:

The third goal is to save money. Small computers often have

better price/performance ratio than the larger ones. Mainframe(room-size) computers are roughly ten faster thanthe personal computers, but are a thousand times costly. Thisimbalance caused thesystem designers to design a systemconsistingofpersonal computers, one peruser, with datakeptononeormoreshared fileservermachines. In this model the userare called the clients and thiswhole arrangement is known astheclient-server model.

In client-server model, the communication generally takes theform ofarequest messagefrom a clienttothereceiveraskingforsomeworktobedone. Serverdoestheworkandsendsbackthereply.


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Scalability:

Anothergoalisscalability. Scalabilityistheabilitytoincreasethesystem performance gradually as the workload grows, by justadding more processors.

Uses of Networks to People

1.Access to Remote Information:

Access to remote informationoccurs in many forms. Oneof theareaswhereitis happeningisaccesstothefinancialinstitutions.Many people pay theirbills, managebankaccountsand handleinvestments electronically. Home shopping is also becomingpopular these days.

Anotherapplicationthatfalls underthis categoryistheaccesstoinformation systems like World Wide Webwhich contains

informationaboutart, business, history, government, geography,economics and several other topics.

Alltheaboveapplicationsinvolvetheinteractionbetweenthe userand a remote database.

2.Person to Person Communication:

Electronic Mail popularly known as email is widely used bymillionsof people tosend text messages, photographsaudioaswellasvideotootherpeopleorgroup ofpeople. Thisapplicationbelongs to person to person communication category.


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Videoconferencingis also becoming popular these days. Thistechnology makes it possibleto havevirtual meetingsamongfarflung people. Itisalsoatypeofpersonto person communication.

3.Interactive Entertainment:

Thesedayswe cansee many live programmesandshows. Thebestthingisthatwe caninteractwith them by participatinginthequizzes and the contests organized by them.


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Advantages and Disadvantages of ComputerNetworks

A computer network is basically a connection of computersand resources like printers, scanners, etc. Here are some of

the advantages and disadvantages of computer

network

s.Advantages

Communication: Even outside of the internet, those on thenetwork can communicate with each othervia electronic mailover the network system. When connected to the internet,network users can communicate with people around theworld via the network.

Increased Storage Capacity: As there is more than onecomputeronanetworkwhich caneasilyshare files, the issueofstorage capacity gets resolved to a great extent. A standalonecomputer might fall short of storage memory, but when manycomputersareonanetwork, memoryofdifferent computers canbe used insuch case. One canalsodesignastorageserveronthenetworkinorderto havea hugestorage capacity.

Increased Cost Efficiency: Thereare manysoftwaresavailable

in the market which are costly and take time for installation.Computer networks resolve this issue as the software can bestoredor installedonasystem oraserverand canbe usedbythedifferentworkstations

File Sharing: The majoradvantageofa computernetworkisthatisallows filesharingand remote fileaccess. A personsittingat

oneworkstationofanetwork caneasilysee the files presentontheotherworkstation, provided heisauthorizedtodoso. Itsavesthe timewhich iswasted in copying a file from one system toanother, by using astorage device. In addition to that, manypeople can access or update the information stored inadatabase, makingit up-to-dateandaccurate.


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Resource Sharing: Resourcesharingisalsoanimportantbenefitofa computernetwork. Forexample, iftherearefourpeopleinafamily, each having their own computer, they will require fourmodems (for the Internet connection) and four printers, if they

wantto usetheresourcesatthesametime. A computernetwork,ontheotherhand, providesa cheaperalternativebythe provisionof resource sharing. In thisway, all the four computers canbeinterconnected, usinganetwork, and justone modem and printercan efficiently provide the services to all four members. Thefacilityofsharedfolders canalsobeavailedbyfamily members.

DisadvantagesofComputerNetworksFollowing are some of the major disadvantages of computer

networks.

Security Issues: One of the major drawbacks of computernetworks is thesecurityissues involved. If a computer is astandalone, physicalaccessbecomesnecessary foranykindofdata theft. However, if a computer is on a network, a

computerhackercanget unauthorizedaccessby usingdifferenttools. In case of big organizations, various network securitysoftwares are used to prevent the theft of any confidential andclassifieddata.

Rapid Spread of Computer Viruses: Ifany computersystem ina network gets affected by computer virus, there is a possiblethreatofothersystemsgettingaffectedtoo.Virusesgetspreadon

anetworkeasilybecauseoftheinterconnectivityofworkstations.Such spread canbedangerous if the computers have importantdatabasewhich canget corruptedbythevirus.

Expensive Set Up: Theinitialset up costofa computernetworkcan be high depending on the number of computers to beconnected. Costlydevices likerouters, switches, hubs, etc., can


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add up tothebillsofa persontryingtoinstalla computernetwork.Hewillalso havetobuyNICs (Network Interface Cards)foreachoftheworkstations, in casetheyarenotinbuilt.

Dependency on the Main File Server: In case the main FileServerofa computernetworkbreaksdown, thesystem becomesuseless. In case of big networks, the File Server should be apowerful computer, which often makesitexpensive.

A person should get well acquainted with the advantages anddisadvantagesofcomputernetworks, beforesettingone up forhispersonal or office use. A knowledge of the pros and cons ofcomputernetworks can help him indesigninga usefulsystem forhimself


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ImportanceofComputerNetworking

Computer Networks are useful in for instance a bank or

office as they need to be able to have a shared area where

data collected by some of them will be able to be used by the

other workers. Networks are also important in schools with

lots of computerrooms as it means the children can log on

to any computer and have their own protected folder. Also it

means that they can put theircomputerwork into the shared

area so that the teachercan mark it without having a massive

pile of papers orbooks.

File Sharing

Computers connected to a network can share files and

documentswith each other. Personal computers connected toa

businessnetwork can choosewhich filesandfoldersareavailable

toshareonthenetwork.

Printers

Computers can print pagestoanothercomputerwith a printeron

thenetwork. Additionally, printers canbe connected usinga print

server, which allowsdirect printingfrom all computers.

Sharing Media

Sharing mediabetween computersiseasywhen connectedtoa

network. Like filesharing, computers canstream musing, videosand moviesfrom one computertothenext.


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Media CenterServer

A media centerserver canstoreyourentireentertainment library

on a centralized hub to give quick access to your media from

every computeronyournetwork.Video Games

Consoleand PC gamersbenefit from networkingalso. You caneasilyset up multiplayerdeath matchesandeven hostyourowngameserver.


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INTRODUCTION TO TYPES OF NETWORKING

Oneway to categorize the different types of computer networkdesigns is by their scope or scale. For historical reasons, thenetworkingindustryreferstonearlyeverytypeofdesignassomekindofarea network. Commonexamplesofareanetwork typesare:

y LAN - Local AreaNetworky WLAN - Wireless Local AreaNetworky WAN - Wide AreaNetworky MAN - Metropolitan AreaNetworky SAN - Storage Area Network, System Area Network, Server

AreaNetwork, orsometimes Small AreaNetworky CAN - Campus Area Network, Controller Area Network, or

sometimes ClusterAreaNetworky PAN - Personal AreaNetworky DAN - Desk AreaNetworkLAN and WAN were the original categories of area networks,while the others have gradually emerged over many years of

technologyevolution.

Note that these network types are a separate concept fromnetworktopologiessuch asbus, ringandstar.


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LAN - local area network (LAN)suppliesnetworking capability

toagroup ofcomputersin close proximitytoeach othersuch as

in an office building, a school, or a home. A LAN is useful for

sharingresourceslikefiles, printers, gamesorotherapplications.A LANinturnoften connectstootherLANs, andtothe Internetor

otherWAN.

Most local area networks are built with relatively inexpensivehardware such as Ethernetcables, network adapters, and hubs.Wireless LANandother moreadvanced LAN hardwareoptionsalsoexist.Specializedoperatingsystem software maybe usedto configure

a local area network. For example, most flavors of MicrosoftWindows provideasoftware package called Internet ConnectionSharing (ICS)thatsupports controlledaccessto LANresources.Itisownedand managedbyone persononly.


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Local Area Network


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WAN - Wide Area Network

Astheterm implies, a WANspansalarge physicaldistance. The

Internetisthelargest WAN, spanningthe Earth.

A WAN is a geographically-dispersed collection of LANs. Anetworkdevice calledarouter connects LANs toa WAN. In IPnetworking, theroutermaintainsboth a LANaddressanda WANaddress.A WANdiffersfrom a LANinseveralimportantways. Most WANs(like the Internet) are not owned by any one organization butrather exist under collective or distributed ownership and

management. WANs tend to use technology like ATM, FrameRelayand X.25forconnectivityoverthelongerdistances.

WAN - Wide Area Network


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Metropolitan Area Network (MAN)

A MAN usually consistsofanumberofinterconnected LANsandWANs, butwillnotextendbeyondtheboundariesofatown, city,

ormetropolitanarea. These A MAN usually consistsofanumberofinterconnected LANsand WANs

MAN technology hasdevelopedsignificantly in recentyears withsmaller networks within a MAN often interconnected wirelesslyusingradio, microwaveorinfra-redlaserlinks

.

Personal Area Network (PAN)

Thesmallest typeofnetwork, a PANsimply involves connectingone person's computer to a number of devices or peripherals.Usually, alldevices, such as printers, PDAs, andtelephones, are


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within a few feet of the computer. A PAN can also refer to aconnection totheinternet.

Campus network


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Campus network

A campus networkis a computer network made up of aninterconnection of local area networks (LANs) within a limitedgeographical area. The networking equipments (switches,routers) and transmission media (optical fiber, copperplant, Cat5 cabling etc.) are almost entirely owned (by thecampus tenant / owner: an enterprise, university, governmentetc.).

In the caseofa university campus-based campusnetwork, thenetwork is likely to linka varietyof campusbuildings including;academic departments, the university library and studentresidence halls.


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d.


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OtherTypes of Area Networks

While LANand WANareby far the most popularnetwork types

mentioned, you may also commonly see references to these

others:

y Wireless Local Area Network - a LANbasedon WiFiwirelessnetworktechnology

y Metropolitan Area Network - a network spanning a physicalarealargerthana LANbutsmallerthana WAN, such asa city.

A MANistypicallyownedanoperatedbyasingleentitysuch asagovernmentbodyorlarge corporation.

y Campus Area Network - anetworkspanning multiple LANsbutsmaller thana MAN, such asona universityor localbusinesscampus.

y Storage Area Network - connects servers to data storagedevicesthrough atechnologylike Fibre Channel.

y System Area Network - links high-performance computerswith

high-speed connections ina cluster configuration. Also knownas ClusterAreaNetwork.


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LAN, WAN and Home Networking

Residencestypicallyemployone LANand connecttothe Internet

WAN via an Internet Service Provider (ISP) using abroadband

modem. The ISP providesa WAN IP addresstothe modem, and

all of the computers on the home network use LAN (so-

calledprivate) IP addresses. All computersonthe home LAN can

communicate directly with each other but must go through a

centralgateway, typicallyabroadbandrouter, toreach the ISP.


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Network topology

In computer networking, topology refers to the layout ofconnecteddevices.

Network topologyis defined as the interconnection of thevarious elements (links, nodes, etc.) of a computernetwork.Network Topologies can be physical or logical.Physical Topology means the physical design of a networkincluding the devices, location and cable installation. Logicaltopologyrefersto howdataisactuallytransferredinanetworkasopposedtoits physicaldesign.

Topology canbe consideredasavirtualshapeorstructureofa

network. Thisshapedoesnot correspond to theactual physicaldesignof thedeviceson the computernetwork. The computersona homenetwork canbearranged ina circlebut itdoesnotnecessarily meanthatitrepresentsaringtopology.

Any particular network topology is determined only by thegraphical mappingof the configurationof physicaland/or logicalconnections between nodes. The study of network topologyusesgraph theory. Distances between nodes, physical

interconnections, transmission rates, and/or signal types maydifferintwonetworksandyettheirtopologies maybeidentical.

A local area network (LAN) is one example of a network thatexhibits both a physical topology and a logical topology. Anygiven node in the LAN has one or more links to one or morenodesinthenetworkandthe mappingoftheselinksandnodesina graph results in a geometric shape that may be used todescribe the physical topology of the network. Likewise, the

mapping of the data flow between the nodes in the networkdeterminesthe logicaltopologyofthenetwork. The physicalandlogical topologies mayor maynotbe identical inany particularnetwork.


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Basic topologytypes

Thestudyofnetworktopologyrecognizessixbasic topologies:

B

ustopology Startopology

Ringtopology

Treetopology

Mesh topology

Hybridtopology

Bustopology

Inlocalareanetworkswherebustopologyis used, each machineis connected to a single cable. Each computer or server isconnected to the single bus cable through some kind ofconnector. A terminator isrequiredateach endofthebus cableto prevent the signal from bouncing back and forth on the bus

cable. A signal from the source travels in both directions to allmachines connected on the bus cable until it finds the MACaddress or IP address on the network that is the intendedrecipient. If the machine address does not match the intendedaddressforthedata, the machineignoresthedata. Alternatively,ifthedatadoes match the machineaddress, thedataisaccepted.Since the bus topology consists of only one wire, it is ratherinexpensive to implement when compared to other topologies.

However, thelow costofimplementingthetechnologyisoffsetbythe high cost of managing the network. Additionally, since onlyone cable is utilized, it canbe the single pointof failure. If thenetwork cablebreaks, theentirenetworkwillbedown.


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Linearbus

The type of network topology in which all of the nodes of thenetworkare connectedtoa commontransmission medium whichhas exactly two endpoints (this is the 'bus', which is also

commonly referred to as thebackbone, ortrunk) alldatathatistransmittedbetween nodes in the network is transmitted overthis commontransmission medium and isable tobereceivedbyall nodes in the network virtually simultaneously(disregarding propagationdelays).

Note: The two endpoints of the common transmission mediumare normally terminated with a device called aterminatorthatexhibitsthe characteristic impedanceofthetransmission medium

andwhich dissipatesorabsorbs theenergy that remains in thesignal to prevent the signal from being reflected or propagatedback onto the transmission medium in the opposite direction,which would cause interference with and degradation of thesignalsonthetransmission medium (See Electricaltermination).

Distributed bus

The type of network topology in which all of the nodes of thenetworkare connectedtoa commontransmission medium which

has morethantwoendpointsthatare createdbyaddingbranchesto the main section of the transmission medium the physicaldistributedbustopologyfunctions inexactlythesamefashionasthe physical linearbus topology (i.e., allnodessharea commontransmission medium).

Notes:

1.) Allof theendpointsof the common transmission medium arenormallyterminatedwith adevice calleda'terminator').

2.) The physical linearbus topology issometimes considered tobeaspecial caseofthe physicaldistributedbustopology i.e., adistributedbuswith nobranchingsegments.

3.) The physicaldistributedbustopologyissometimesincorrectlyreferred toasa physical tree topology however, although thephysical distributed bus topology resembles the physical tree


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topology, itdiffersfrom the physicaltreetopology inthatthere isno centralnode towhich anyothernodesare connected, sincethis hierarchicalfunctionalityisreplacedbythe commonbus.

Star topology

In localareanetworkswith astartopology, each network host isconnected toa central hub. In contrast to thebus topology, thestartopology connectseach nodetothe hubwith a point-to-pointconnection. Alltraffic thattransversesthenetwork passesthroughthe central hub. The hubactsasasignalboosterorrepeater. Thestar topology is considered the easiest topology to design and

implement. Anadvantageof thestar topology is thesimplicityofadding additional nodes. The primary disadvantage of the startopologyisthatthe hubrepresentsasingle pointoffailure.

A point-to-point link (described above) is sometimescategorizedasaspecial instanceofthe physicalstartopology


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therefore, thesimplesttypeofnetworkthatisbased uponthephysicalstartopologywould consistofonenodewith asinglepoint-to-point link toasecondnode, the choiceofwhich nodeisthe'hub'andwhich nodeisthe'spoke'beingarbitrary.

After thespecial caseof the point-to-point link, as innote 1.)above, thenextsimplesttypeofnetworkthatisbased uponthephysicalstartopologywould consistofone centralnode the'hub' with twoseparate point-to-point links to two peripheralnodes the'spokes'.

Although mostnetworksthatarebased uponthe physicalstartopology are commonly implemented using a special devicesuch asa huborswitch as the centralnode (i.e., the 'hub'ofthe star), it is also possible to implement a network that isbased upon the physical star topology using a computer orevenasimple common connection pointasthe'hub'orcentralnode however, since many illustrationsof the physical starnetwork topology depict the central node as one of thesespecialdevices, some confusionis possible, sincethis practicemay lead to the misconception that a physical star network

requires the centralnode tobeoneof thesespecialdevices,which isnottruebecauseasimplenetwork consistingofthreecomputers connected as in note 2.) above also has thetopologyofthe physicalstar.

Starnetworks mayalsobedescribedaseitherbroadcast multi-accessornon broadcast multi-access (NBMA), depending onwhether the technology of the network either automaticallypropagatesasignalatthe hubtoallspokes, oronlyaddressesindividualspokeswith each communication.


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Ring topology

In local area networks where the ring topology is used, each

computer is connected to the network in a closed loop or ring.Each machineorcomputerhasa uniqueaddressthatis usedfor

identification purposes. Thesignal passesthrough each machine

or computer connected to the ring in one direction. Ring

topologies typically utilize a token passing scheme, used to

controlaccess tothenetwork.By utilizing thisscheme, onlyone

machine cantransmitonthenetworkatatime. The machinesor

computers connected to the ring act as signal boosters orrepeaters which strengthen the signals that transverse the

network. The primarydisadvantageofring topology isthe failure

ofone machinewill causetheentirenetworktofail.

Mesh topology

The value of fully meshed networks is proportional to theexponent of the number of subscribers, assuming thatcommunicatinggroupsofanytwoendpoints, up toand includingalltheendpoints, isapproximatedby Reed's Law.

Fully connected mesh topology

Thenumberofconnectionsinafull mesh = n(n - 1)/2

Fully connectedNote: The physical fully connected mesh topology isgenerally too costly and complex for practical networks,although the topology is usedwhen thereareonlyasmallnumberofnodestobeinterconnected.


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Partially connected

Thetypeofnetworktopologyinwhich someofthenodesofthenetworkare connected to more thanoneothernode inthenetworkwith a point-to-pointlink this makesit possible

to take advantage of some of the redundancy that isprovided by a physical fully connected mesh topologywithout the expense and complexity required for aconnectionbetweeneverynodeinthenetwork.

Note: In most practical networks that are based upon thephysical partially connected mesh topology, allof thedatathat is transmittedbetweennodes in thenetwork takes theshortest path (or an approximation of the shortest path)

betweennodes, except in the caseofa failureorbreak inoneofthe links, inwhich casethedatatakesanalternativepath to thedestination. This requires that thenodesof thenetwork possesssome typeof logical 'routing'algorithm todeterminethe correct path to useatany particulartime.

Network classification

The following list presents categories used for classifyingnetworks.

Connection method

Computernetworks canbe classifiedaccording to the hardwareandsoftwaretechnologythatis usedtointerconnecttheindividualdevices in the network, such asoptical fiber, Ethernet, WirelessLAN, Home PNA, Powerline communicationorG.hn.

Ethernet uses physical wiring to connect devices. Frequentlydeployeddevices include hubs, switches, bridgesand/orrouters.Wireless LAN technology isdesigned to connectdeviceswithoutwiring. These devices useradio wavesorinfraredsignals as atransmission medium. ITU-T G.hntechnology usesexisting home


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wiring (coaxial cable, phone lines and power lines) to create ahigh-speed (up to 1 Gigabit/s)localareanetwork.

Wired technologies

Twisted pairwireis the most widely used medium fortelecommunication. Twisted-pairwiresareordinary telephonewireswhich consistof two insulated copperwires twisted intopairsandare used forboth voiceanddata transmission. Theuse of two wires twisted together helps toreduce crosstalkandelectromagnetic induction. Thetransmission speed ranges from 2 million bits per second to100 millionbits persecond.

Coaxial cableiswidely usedforcabletelevisionsystems, officebuildings, and other worksites for local area networks. Thecables consist of copper or aluminum wire wrapped withinsulating layer typically of a flexible material with a highdielectric constant, allofwhich aresurroundedbya conductivelayer. The layersof insulation help minimize interferenceanddistortion. Transmissionspeedrange from 200 millionto morethan500 millionbits persecond.

Optical fiber cable consists of one or more filaments of glassfiberwrapped in protective layers. It transmits lightwhich cantravel over extended distances. Fiber-optic cables are notaffectedbyelectromagnetic radiation. Transmissionspeed mayreach trillions of bits per second. The transmission speed offiberoptics is hundredsof times faster than for coaxial cablesandthousandsoftimesfasterthanatwisted-pairwire]Wireless

technologies

Terrestrial Microwave Terrestrial microwaves use Earth-based transmitterand receiver. Theequipment looksimilar tosatellite dishes. Terrestrial microwaves use low-gigahertzrange, which limits all communications to line-of-sight. Path


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between relay stations spaced approx. 30 miles apart.Microwave antennas are usually placed on top of buildings,towers, hills, and mountain peaks.

Communications Satellites The satellites use microwaveradio as their telecommunications medium which are notdeflected by the Earth's atmosphere. The satellites arestationed inspace, typically22,000 miles (forgeosynchronoussatellites)abovetheequator. These Earth-orbitingsystemsarecapableofreceivingandrelayingvoice, data, and TVsignals.

Cellular and PCS Systems Use several radiocommunications technologies. The systems are divided todifferent geographic areas. Each area has a low-powertransmitterorradiorelayantennadevicetorelay callsfrom oneareatothenextarea.

Wireless LANs Wireless local area network use a high-frequencyradiotechnologysimilartodigital cellularandalow-frequency radio technology. Wireless LANs use spreadspectrum technology to enable communication between

multiple devices in a limited area. An example of open-standardswirelessradio-wavetechnologyis IEEE

Infrared communication , which can transmit signals betweendeviceswithinsmalldistancesnot morethan 10 meters peertopeer or ( face to face ) without any body in the line oftransmitting.

Scale

Networks are often classified aslocal area network (LAN), wideareanetwork (WAN), metropolitanareanetwork (MAN), personalarea network (PAN), virtual private network (VPN), campus areanetwork (CAN), storage area network (SAN), and others,dependingontheirscale, scopeand purpose, e.g., controllerareanetwork (CAN) usage, trust level, and access right often differ


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between these typesofnetworks. LANs tend tobedesigned forinternal usebyanorganization'sinternalsystemsandemployeesin individual physical locations, such asabuilding, while WANsmay connect physically separate parts of an organization and

mayinclude connectionstothird parties.

Functional relationship (network architecture)

Computernetworks maybe classifiedaccordingtothefunctionalrelationships which exist among the elements of the network,e.g., active networking, clientserverand peer-to-peer(workgroup)architecture.


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Network Cables and Cabling

Network cableis used to connect and transfer data betweencomputers and anetwork. There are different typesofnetworkcable, and theappropriate type to usewilldependonthe structure and topology of yournetwork. Different types ofcableareasfollows;

Category 5 cable

Category5 cableisatwisted pairhigh signal integrity cable type

often referred to as Cat5orCat-5. Most Category-5 cables

are unshielded, relying on the twisted pair design fornoiserejection. Category 5 has been superseded by the Category

5especification. This type of cable is used instructured

cablingforcomputernetworkssuch as Ethernetand ATM, and is

also used to carry many other signals such astelephony

andvideo.

Connectors and other information

The cableexistsinboth strandedandsolid conductorforms. Thestranded form is more flexible and withstands more bendingwithout breaking and is suited for reliable connectionswith insulation piercing connectors, but makes unreliableconnectionsininsulation-displacement connectors. Thesolidformis lessexpensiveand makes reliable connections into insulationdisplacement connectors, but makes unreliable connections ininsulation piercing connectors. Taking these things intoaccount,building wiring (for example, the wiring inside the wall thatconnects awall socket to a central patch panel) is solid core,while patch cables (forexample, the movable cablethat plugsintothewall socket on one end and a computer on the other) arestranded. Outerinsulationistypically PVC orLSOH.


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Cable types, connector typesand cabling topologiesaredefinedby TIA/EIA-568-B. Nearly always, 8P8C modular connectors,often incorrectly referred toas "RJ-45", are used for connectingcategory5 cable. The specific categoryof cable in use canbe

identifiedbythe printingonthesideofthe cable.[3]

The cableisterminatedineitherthe T568A schemeorthe T568Bscheme. Canadaand Australia usethe T568A standard, andtheUnited States commonly uses T568B scheme. It really doesn'tmakeanydifferencewhich is usedaslongasyou useonlyoneofthestandardssoall connectionsarethesameatyourlocationtoavoid confusionand potential problems. Mixed cabletypesshouldnot be connected in series as the impedance per pair differs

slightly and may cause signal degradation. The article Ethernetover twisted pairdescribes how the cable is used for Ethernet,includingspecial"crossover" cables.

Conductors required

10BASE-T (IEEE)and 100BASE-TX (IEEE) Ethernet connectionsrequire two cable pairs. 1000BASE-T (IEEE)and 1000BASE-TX(TIA/EIA-854, requiring category6 cabling) Ethernet connectionsrequirefourcable pairs. Fourpaircableisbyfarmost commonlyavailabletype.

Characteristics

Electrical characteristicsforCat.5e UTP

Property Nominal Value

Tolerance

Unit ref

Characteristic impedance @100 MHz

100 15 [5]


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Nominal characteristic impedance @ 100 MHz

100 5 [5]

DC-Loop resistance 0.188 /m [5]

Propagation speed 0.64 c [5]

Propagation delay 4.80-5.30

ns/m

[5]

Delay skew < 100 MHz < 0.20 ns/m

[5]

Capacitance at 800 Hz 52 pF/m

[5]

Inductance 525 nH/m

[6]

Cutoff frequency 50323 Hz[6]

Max tensile load, duringinstallation

100 N [5]

Wire size AWG-

24 (0.205 mm )

[5][7

]

Insulation thickness 0.245 mm [5]


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Maximum current perconductor

0.577 A [7]

Temperature operating -55 to+60

C [5]

Patch cables

A patch cable connects twonetworkdevices. Patch cablesaretypically CAT5 / CAT5e Ethernet cables linking a computer to a

nearbynetwork hub, switch orrouter.

Ethernet patch cablesare usefultothosebuilding home computernetworksandalsototravelerswhoneedwiredaccessto Internetconnections such as those provided in hotel rooms. They arenormally manufactured usingstrandedratherthansolidsheathing

inordertogivethem pliabilitythatreducesriskofbreakagewhenunpluggingorcarryingthem.

A crossover cableisaspecific typeofEthernet patch cable usedtodirectly connecttwo computerstoeach other.


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Fiber opticpatch cables are also commonly used in thenetworking. The term patch cordis sometimes usedsynonymouslywith patch cable, although patch cordsareoftennon-network types of cables such as those for wiring stereo

components.

Category5e Patch Cablesare used for cross-connecting PatchPanels and Hubs as well as connecting the PC to the walloutlet. Patch Cables come instandard lengthsbutareavailablein custom lengthsalso. Please contactNetwork Supply Inc. forpricingon custom lengths.

Our Spectrum Category 5E 350MHzbooted premium patch cables offer the

followingfeaturesandbenefits:

y Injection molded boots for criticalCategory 5E bend radiusrequirements and sealing of theplug/cableinterface

y

"Flush" mold design to allow bootedPatch Cables to be installed side bysidein High-Density patch fields

y Two stock Options, Flush "Bump"style for a protected clip and Flush"Bumpless" fora molded strain reliefwith no clip coverage

y 50 Shortbody plugsforminimal "de-twisting" of the cable pairs during

manufacturingy 24AWG stranded construction for

minimum flexibilityy 24AWG solid on applicable PVC of

Plenum cablesy Compliancewith EIA/TIA Category5E


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specificationsy Lifetimewarranty

STANDARD LENGTHS

(Please select desired length)1 Foot 2 Foot

3 Foot 5 Foot

6 Foot 7 Foot

10 Foot 14 Foot

25 Foot 50 Foot

75 Foot 100 Foot

Fiber Optic Cable

Thefiberoptic cable consistsof1 mm Plastic Optical Fiber(POF)or200 m Hard Clad Silica (HCS) (glass) multi-modeopticalfiberwith astep index profileorgradedindex profile. Fiberoptic cablesand cores canbe used. Onlyfiberoptic cableswith awavelength

of 650 nm are specified for SERCOS. For fiber optic materialscurrently in use, theattenuation isapproximately220 dB/km forplastic and 6 dB/km for glass.

The following drawing illustrates the structure of a typical fiberoptic cable.Note that the SERCOS interfacestandarddoesnotspecify the outer diameter of the cables. Typically, 2.2 mmdiameter cables are used inside equipment cabinets. These

cablesdonot have thestrength membersshown inthedrawing.Typically, 3.6, 5and6 mm diameter cablesare usedforcabinet-to-cabinet connections.

Structure of a single-core fiberoptic cable


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SPEED: Fiberoptic networksoperateat high speeds - up intothe gigabitsBANDWIDTH:large carrying capacityDISTANCE: Signals canbe transmitted furtherwithoutneeding

to be "refreshed" or strengthened.RESISTANCE: Greater resistance to electromagnetic noisesuch as radios, motors or other nearby cables.MAINTENANCE: Fiber optic cables costs much less tomaintain.

In recent years it has become apparent that fiber-optics are

steadily replacing copper wire as an appropriate means ofcommunicationsignaltransmission. Theyspanthelongdistancesbetween local phonesystemsaswellas providing thebackbonefor many network systems. Other system users include cabletelevision services, university campuses, office buildings,industrial plants, andelectric utility companies.

A fiber-optic system issimilartothe copperwiresystem thatfiber-optics is replacing. The difference is that fiber-optics use light

pulses to transmit information down fiber lines instead of usingelectronic pulses to transmit information down copper lines.Lookingatthe componentsinafiber-optic chainwillgiveabetterunderstandingof how thesystem works in conjunctionwith wirebasedsystems.

At one end of the system is a transmitter. This is the place oforigin for information coming on to fiber-optic lines. Thetransmitter accepts coded electronic pulse information comingfrom copper wire. It then processes and translates thatinformation into equivalently coded light pulses. A light-emittingdiode (LED) or an injection-laser diode (ILD) can be used forgenerating the light pulses. Using a lens, the light pulses arefunneled into the fiber-optic medium where they traveldown the


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cable. The light (near infrared) is mostoften850nm for shorterdistancesand 1,300nm for longerdistanceson Multi-mode fiberand 1300nm for single-mode fiber and 1,500nm is used for forlongerdistances.

Thinkofafibercableintermsofverylong cardboardroll (from theinside roll of paper towel) that is coated with a mirror on theinside.Ifyou shineaflashlightinoneendyou canseelight comeoutatthefarend - evenifit'sbeenbentarounda corner.

Light pulses moveeasilydown the fiber-optic linebecauseofaprincipleknownas total internalreflection. "This principleof totalinternalreflectionstatesthatwhentheangleofincidenceexceedsa criticalvalue, light cannotgetoutoftheglass;instead, thelightbouncesbackin. Whenthis principleisappliedtothe constructionofthefiber-optic strand, itis possibletotransmitinformationdownfiber lines in theform of light pulses. The core mustavery clearand pure materialforthelightorin most casesnearinfraredlight(850nm, 1300nm and 1500nm). The core canbe Plastic (usedforveryshortdistances)but mostare madefrom glass. Glassoptical

fibersarealmostalways made from puresilica, butsomeothermaterials, such asfluorozirconate, fluoroaluminate,and chalcogenideglasses, are used for longer-wavelengthinfraredapplications.

Therearethreetypesoffiberoptic cable commonly used:singlemode, multimode and plastic optical fiber (POF).

Transparentglassor plastic fiberswhich allow light tobeguidedfrom oneendtotheotherwith minimalloss.


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Fiber optic cable functions as a "light guide," guiding the lightintroducedatoneendofthe cablethrough totheotherend. Thelightsource caneitherbealight-emittingdiode (LED))oralaser.

The light source is pulsed on and off, and a light-sensitivereceiveron theotherendof the cable converts the pulsesbackintothedigitalonesandzerosoftheoriginalsignal.

Even laser lightshining through a fiberoptic cable issubject tolossofstrength, primarilythrough dispersionandscatteringofthelight, within the cable itself. The faster the laser fluctuates, thegreater the risk of dispersion. Light strengtheners, called


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repeaters, may be necessary to refresh the signal in certainapplications.

While fiberoptic cable itself hasbecome cheaperover time - a

equivalent length of copper cable cost less per foot but not incapacity. Fiberoptic cable connectorsandtheequipmentneededto install them are still more expensive than their coppercounterparts.

Single Mode cableis a single stand (most applications use 2fibers)ofglassfiberwith adiameterof8.3 to 10 micronsthat hasone mode of transmission. Single Mode Fiberwith a relativelynarrow diameter, through which only one mode will propagatetypically 1310 or 1550nm. Carries higher bandwidth thanmultimodefiber, butrequiresalightsourcewith anarrowspectralwidth. Synonyms mono-mode optical fiber, single-mode fiber,single-modeopticalwaveguide, uni-modefiber.

Single Modem fiber is used in manyapplicationswheredata issent at multi-frequency (WDM Wave-Division-Multiplexing) soonlyone cableisneeded - (single-modeononesinglefiber)

Single-modefibergivesyou a highertransmissionrateand up to50 times moredistance than multimode, but italso costs more.Single-mode fiberhasa much smaller corethan multimode. Thesmall coreandsingle light-wavevirtuallyeliminateanydistortionthat couldresultfrom overlappinglight pulses, providingtheleastsignal attenuation and the highest transmission speeds of anyfiber cable type.

Single-mode optical fiber is an optical fiber in which only thelowest order bound mode can propagate at the wavelength ofinteresttypically 1300 to 1320nm.


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jump tosingle modefiberpage

Multi-Mode cable hasa littlebitbiggerdiameter, with a commondiameters in the 50-to-100 micron range for the light carrycomponent (in the US the most common size is 62.5um). Mostapplications inwhich Multi-mode fiber is used, 2 fibersare used(WDM isnotnormally usedon multi-modefiber). POF isanewer

plastic-based cablewhich promises performancesimilar toglasscableonveryshortruns, butatalowercost.

Multimode fibergivesyou high bandwidth at high speeds (10 to100MBS - Gigabitto275m to2km)overmedium distances. Lightwaves are dispersed into numerous paths, or modes, as theytravel through the cable's core typically850 or 1300nm. Typicalmultimode fiber core diameters are 50, 62.5, and 100micrometers. However, inlong cableruns (greaterthan 3000 feet

[914.4 meters), multiple pathsof light can causesignaldistortionat thereceivingend, resulting inan unclearand incompletedatatransmissionsodesignersnow call forsingle mode fiber innewapplications using Gigabitandbeyond.


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The use of fiber-optics was generally not available until 1970when Corning Glass Workswas able to producea fiberwith alossof20 dB/km. Itwas recognized thatoptical fiberwouldbefeasiblefortelecommunicationtransmissiononlyifglass couldbedeveloped so pure that attenuationwould be 20dB/km or less.Thatis, 1% ofthelightwouldremainaftertraveling 1 km. Today's

optical fiber attenuation ranges from 0.5dB/km to 1000dB/kmdependingontheopticalfiberused. Attenuation limitsarebasedonintendedapplication.

Theapplicationsofoptical fiber communications have increasedata rapid rate, since the first commercial installationofa fiber-


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optic system in 1977. Telephone companies began early on,replacing their old copperwire systemswith optical fiber lines.Today's telephone companies use optical fiber throughout theirsystem as the backbone architecture and as the long-distance

connectionbetween city phonesystems.

Cable television companies have also began integrating fiber-optics into their cable systems. The trunk lines that connectcentral offices have generally been replaced with optical fiber.Some providers havebegunexperimentingwith fiber to the curbusing a fiber/coaxial hybrid. Such a hybrid allows for theintegrationof fiberand coaxialataneighborhood location. Thislocation, called a node, would provide the optical receiver thatconvertsthelightimpulsesbacktoelectronic signals. Thesignalscouldthenbefedtoindividual homesvia coaxial cable.

Local AreaNetworks (LAN)isa collectivegroup ofcomputers, orcomputersystems, connected toeach otherallowing forsharedprogram software or data bases. Colleges, universities, office


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buildings, and industrial plants, justtonameafew, all make useofopticalfiberwithintheirLANsystems.

Power companies are an emerging group that have begun to

utilize fiber-optics in their communication systems. Most powerutilitiesalready havefiber-optic communicationsystemsin useformonitoringtheirpowergridsystems.

Cable Specifications

Plastic Fiber -POF

Glass Fiber -HCS

Corediameter 980 m 200 m

Claddingdiameter

1000 m 230 m

Numeric 0.47 0.37


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aperture

Bandwidth >= 5 MHz * 1km

>= 10 MHz *1 km

Fiber Optic Connectors

SERCOS fiber optic cable connectors are specified as:-- Shall correspond to F-SMA standard (see IEC 60874-2).-- Shall have a quality level of at least 5.-- Shall have a metallic connector ring.

Inaddition, itisrecommendedthatfiberoptic cables haveastrain

relief.

Fiber Optic Ring Lengths

A SERCOS interfaceringis composedofanumberoffiber-opticsegments. Maximum cablelengthsare:

Cable Type MaximumCable Length

Plastic fiber POF (1 mmdiameter)

Node-to-node 40 meters

Maximum ring length(254 nodes perring)

10,000+ meters

Glass fiber HCS (200m diameter)

Node-to-node 200 metersMaximum ring length(254 nodes perring)

50,000+ meters

Ifa coupling is used to passa cable through a cabinetwall, themaximum length of that segment is reduced by 6 meters.


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The maximum number of drops per fiber-optic ring is 254.However, the number of drives that can be serviced per ringdepends on three application requirements:

-- The communication cycle time.-- The volume of operational data.-- The communications speed required.

Thenumberofringsthat canbesynchronizedtogether is limitedonly by the controller, which will have a limit to the number ofaxesit can process. SERCOS interface-compliant controllers canhavea much higheraxis limit than their predecessors, since the

SERCOS interface supports distributed processing, whichrelieves the controller of many time-intensive tasks, which arenow handled by the drives.


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Performance ofSERCOS interface Rings -- Generation I andII

CycleTime

DataRecord

PerDrive(MDT +AT)

TransmissionRate

Numberof

Drives

DataRate

(Non-cyclicData)

RemainingCycle

Time

2 ms 32Bytes 2 Mbit/sec 8 8kbit/s(2bytes)

390s


125s


208s

0.5ms

36Bytes 16 Mbit/sec 14 128kbit/s

(8bytes)

113s

2 ms StandardTelegram2,3,4

16 Mbit/sec 112 8kbit/s(2bytes)

330s


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