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1.To study the colour coding of RJ-45 along with the categories of networks.

Ans: Categories of Networks: Today when we speak of networks, we are generally referring to two priary categories: local-area networks and

wide-area networks. The category into which a network falls is deterined !y its si"e. A #A$ norally co%ers an area less than & i' a (A$ can

!e worldwide. $etworks of a si"e in !etween are norally referred to as etropolitan area networks and span tens of iles.

Local Area Network: A local area network )#A$* is usually pri%ately owned and links the de%ices in a single office, !uilding, or capus

+epending on the needs of an organi"ation and the type of technology used, a #A$ can !e as siple as two s and a printer in soeones hoeoffice' or it can e/tend throughout a copany and include audio and %ideo peripherals. urrently, #A$ si"e is liited to a few kiloeters#A$s

are designed to allow resources to !e shared !etween personal coputers or workstations. The resources to !e shared can include hardware )e.g.,

a printer*, software )e.g., an application progra*, or data. A coon e/aple of a #A$, found in any !usiness en%ironents, links a

workgroup of task-related coputers, for e/aple, engineering workstations or accounting s. 0ne of the coputers ay !e gi%en a large

capacity disk dri%e and ay !ecoe a ser%er to clients. oftware can !e stored on this central ser%er and used as needed !y the whole group. 2n

this e/aple, the si"e of the #A$ ay !e deterined !y licensing restrictions on the nu!er of users per copy of software, or !y restrictions on

the nu!er of users licensed to access the operating syste. 2n addition to si"e, #A$s are distinguished fro other types of networks !y their

transission edia and topology. 2n general, a gi%en #A$ will use only one type of transission ediu. Today, speeds are norally 133 or

1333 !ps. (ireless #A$s are the newest e%olution in #A$ technology.

Wide Area Network:A wide area network pro%ides long-distance transission of data, iage, audio, and %ideo inforation o%er large

geographic areas that ay coprise a country, a continent, or e%en the whole world. A (A$ can !e as cople/ as the !ack!ones that connect the

2nternet or as siple as a dial-up line that connects a hoe coputer to the 2nternet. (e norally refer to the first as a switched (A$ and to the

second as a point-to-point (A$ )igure 1.11*. The switched (A$ connects the end systes, which usually coprise a router )internetworking

connecting de%ice* that connects to another #A$ or (A$. The point-to-point (A$ is norally a line leased fro a telephone or ca!le T6

pro%ider that connects a hoe coputer or a sall #A$ to an 2nternet ser%ice pro%ider )l*. This type of(A$ is often used to pro%ide 2nternetaccess.An early e/aple of a switched (A$ is 7.&5, a network designed to pro%ide connecti%ity !etween end user. 7.&5 is !eing gradually

replaced !y a high-speed, ore efficient network called rae Relay. A good e/aple of a switched (A$ is the asynchronous transfer ode

)AT* network, which is a network with fi/ed-si"e data unit packets called cells. Another e/aple of (A$s is the wireless (A$ that is

!ecoing ore and ore popular.

Metropolitan Area Networks: A etropolitan area network )A$* is a network with a si"e !etween a #A$ and a (A$. 2t norally co%ers the

area inside a town or a city. 2t is designed for custoers who need a high-speed connecti%ity, norally to the 2nternet, and ha%e endpoints spread

o%er a city or part of city. A good e/aple ofa A$ is the part of the telephone copany network that can pro%ide a high-speed +# line to the

custoer. Another e/aple is the ca!le T6 network that originally was designed for ca!le T6, !ut today can also !e used for high-speed data

connection to the 2nternet.

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Interconnection of Networks: Internetwork Today, it is %ery rare to see a #A$, a A$, or a #A$ in isolation' they are connected to one

another. (hen two or ore networks are connected, they !ecoe an internetwork, or internet. As an e/aple, assue that an organi"ation has

two offices, one on the east coast and the other on the west coast. The esta!lished office on the west coast has a !us topology #A$' the newly

opened office on the east coast has a star topology #A$. The president of the copany li%es soewhere in the iddle and needs to ha%e control

o%er the copany fro her hoe. To create a !ack!one (A$ for connecting these three entities )two #A$s and the presidents coputer*, a

switched (A$ )operated !y a ser%ice pro%ider such as a teleco copany* has !een leased. To connect the #A$s to this switched (A$,

howe%er, three point-to-point (A$s are re8uired. These point-to-point (A$s can !e a high-speed +# line offered !y a telephone copany or a

ca!le odern line offered !y a ca!le T6 pro%ider as shown in igure 1.1&.

Connectors:The ost coon 9T connector is RJ45 )RJ stands for registered ack*. The RJ45 is a keyed connector, eaning the connector

can !e inserted in only one way.

Twisted pair wire actually contains 4 pairs of wire !ut only two of the pairs are used. The standards designate those pairs as the ;reen pair and

the 0range pair. The < are actually opposites of each other.$ote that pins 4, 5, ?, and > and the !lue and !rown pairs arenot used in either standard. @uite contrary to what you ay read elsewhere, these pins and wires are not used or re8uired to ipleent

133A and 2ABT2A 5=>

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&. (hat are the classes of transission edia and also e/plain wireless ediu in detail.

Ans: 2n telecounications, transission edia can !e di%ided into two !road categories: guided and unguided. ;uided edia includetwisted-pair ca!le, coa/ial ca!le, and fi!er-optic ca!le. 9nguided ediu is free space shows this ta/onoy.

Guided media:

;uided edia, which are those that pro%ide a conduit fro one de%ice to another, include twisted-pair ca!le, coa/ial ca!le, and fi!er-optic

ca!le. A signal tra%eling along any of these edia is directed and contained !y the physical liits of the ediu. Twisted-pair and coa/ial

ca!le use etallic )copper* conductors that accept and transport signals in the for ofelectric current. 0ptical fi!er is a ca!le that accepts

and transports signals in the for of light.

Twisted-air a!le.A twisted pair consists of two conductors )norally copper*, each with its own plastic insulation, twisted together

0ne of the wires is used to carry signals to the recei%er, and the other is used only as a ground reference. The recei%er uses the difference

!etween the two suppose in one twist, one wire is closer to the noise source and the other is farther' in the ne/t twist, the re%erse is trueTheunwanted signals are ostly canceled outThe ost coon twisted-pair ca!le are )A*unshielded twisted-pair )9T*,)

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A fi!er-optic ca!le is ade of glass or plastic and transits signals in the for of light0ptical fi!ers use reflection to guide light through achannel. A glass or plastic core is surrounded !y a cladding of less dense glass or plastic. The difference in density of the two aterials ust !e

such that a !ea of light o%ing through the core is reflected off the cladding instead of !eing refracted into it.

0ptical fi!ers are defined !y the ratio of the diaeter of their core to the diaeter of their cladding, !oth e/pressed in icroeters.Theouteracket is ade ofeither6 or Teflon. 2nside theacketare De%lar strands to strengthen the ca!le. De%lar is a strong aterial used in the

fa!rication of!ulletproof%ests.