Recognize the physical topology of a network

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					                               PRACTICAL - 1
AIM: - Familiarization with Computer Hardware




CD ROM




A CD-ROM drive uses an optically read plastic coated disk. The information is recorded on the
surface of the disk in small holes aligned along a spiral from the center to edge. The drive directs
a laser beam along the spiral to read the disk. When the laser hits the hole the laser is reflected in


                                                 [1]
the one way, when it hits the smooth surface it is reflected in another way. This makes it easy to
code bits and therefore information. The rest is easy, mere mechanics. Short form is Compact
Disk Read Only Memory. CD ROM drives are CD players inside of the computer that can range
of speed from 1x and beyond and has the capability of playing audio CDs and also computer data
CDs. Internal picture of a CD_ROM is shown below.CD-ROM, in computer science, acronym
for compact disc read-only memory, a rigid plastic disk that stores a large amount of data
through the use of laser optics technology. Because they store data optically, CD-ROMs have a
much higher memory capacity than computer disks that store data magnetically. However, CD-
ROM drives, the devices used to access information on CD-ROMs, can only read information
from the disc, and not write to it. CD-ROMs and Audio CDs are almost exactly alike in structure
and data format. The difference between the two lies in the device used to read the data—either a
CD-ROM player or a compact disc (CD) player. CD-ROM players are used almost exclusively
as computer components or peripherals. They may be either internal (indicating they fit into a
computer‘s housing) or external (indicating they have their own housing and are connected to the
computer via an external port).


Both types of players spin the discs to access data as they read the data with a laser device. CD-
ROM players only spin the disc to access a sector of data and copy it into main memory for use
by the computer, while audio CDs spin throughout the time that the audio recording is read out,
directly feeding the signal to an audio amplifier.


The most important distinguishing feature among CD-ROM players is their speed, which
indicates how fast they can read data from the disc. A single-speed CD-ROM player reads
150,000 bytes of data per second. Double-speed (2X), triple-speed (3X), quadruple-speed (4X),
six-time speed (6X), and eight-times speed (8x) CD-ROM players are also widely available.


Other important characteristics of CD-ROM players are seeking time and data transfer rate. The
seek time (also called the access time) measures how long it takes for the laser to access a
particular segment of data. A typical CD-ROM takes about a third of a second to access data, as
compared to a typical hard drive, which takes about 10 milliseconds (thousandths of a second) to
access data. The data transfer rate measures how quickly data is transferred from the disk media
to the computer‘s main memory.
                                                 [2]
                                 CD-ROM




                                 COMPACT DISK




Storing Data on Compact Discs

Data stored on a compact disc (CD) and on two variations of the CD, the compact disc-
recordable (CD-R) and the compact disc-rewriteable (CD-RW), is read by bouncing a low-



                                         [3]
powered laser off the disc and analyzing the reflection. The three formats differ, however, in the
method employed to record data. On a CD, data is stored as a pattern of unreflective pits pressed




into a layer of highly reflective aluminum (Al) at a factory. On a CD-R, a higher-powered laser
burns areas of a transparent dye that lies over a reflective layer, turning specks of dye opaque and
creating virtual pits that prevent the lower-powered read laser from being reflected. Once burned
the dye cannot be made transparent again. A CD-RW has a layer of metal phase-change film that
can switch between a highly reflective phase and a no reflective phase. When a higher-powered
laser melts specks of the metal film, the specks cool quickly and become non-reflective, similar
to the pits on a CD. However, the metal film can be made reflective again (erased) by heating it
with a medium-powered laser that allows the film to cool slowly. Two layers of dielectric film
sandwich the metal film and help


The underside of the plastic CD-ROM disk is coated with a very thin layer of aluminum that
reflects light. Data is written to the CD-ROM by burning microscopic pits into the reflective
surface of the disk with a powerful laser. The data is in digital form, with pits representing a
value of 1 and flat spots, called land, representing a value of 0. Once data is written to a CD-
ROM, it cannot be erased or changed, and this is the reason it is termed read-only memory. Data
is read from a CD-ROM with a low power laser contained in the drive that bounces light—
usually infrared—off of the reflective surface of the disk and back to a photo detector. The pits in
the reflective layer of the disk scatter light, while the land portions of the disk reflect the laser
light efficiently to the photo detector. The photo detector then converts these light and dark spots
to electrical impulses corresponding to 1s and 0s. Electronics and software interpret this data and
accurately access the information contained on the CD-ROM.


CD-ROMs can store large amounts of data and so are popular for storing databases and
multimedia material. The most common format of CD-ROM holds approximately 630
megabytes (see Byte). By comparison, a regular floppy disk holds approximately 1.44
megabytes.


The computer industry also manufactures blank, recordable compact discs, called CD-Rs
(compact disc-recordable), that users can record data onto for one-time, permanent storage using
                                               [4]
CD-R drives. Compact disc-rewriteable (CD-RWs) are similar to CD-Rs, but can be erased and
rewritten multiple times. Another technology that allows the user to write to a compact disc is
the magneto-optical (MO) disk, which combines magnetic and optical data storage. Users can




record, erase, and save data to these disks any number of times using special MO drives. A CD is
encoded with tiny pits that are arranged to represent the binary code of the recorded material. A
laser beam is used to read the binary code off of the reflective surface of the disc. The light beam
is either reflected back from the flat surface or dispersed when the beam strikes a pit. A sensor
records whether the light is reflected or dispersed, and based on these changing values, the CD
player reconstructs the original binary code of the recorded sound.


The digital audio format of a CD allows for more than one hour of stereo music. The diameter of
a disc is 12.07 cm (4.75 in). The data are recorded from the inside of the disc outwardly in a
continuous spiral of tracks. CDs can also be used for digital storage of photographs, film and
video footage, software, or any combination of these.


Videodiscs, which are larger than CDs and hold much more information, are used for storage of
film. Many feature-length movies are available in this format. Videodiscs are 30.48 cm (12.00
in) in diameter and can be recorded on both sides. Digital Video Discs (DVDs) are replacing
videodiscs as a format for viewing movies and are also popular as a format for large multimedia
programs for computers. DVDs are the same size as CDs but are more densely recorded, so more
information can be fitted on a disc.


A blank MD is recordable. It uses what is called magneto-optical technology to record and play
music. Instead of pits and smooth surfaces, a blank MD uses tiny magnetic particles embedded
within the shiny surface of the MD to store the digital code. To record digital data on an MD, a
laser heats very small spots on the surface of the MD for a fraction of a second. An
electromagnetic recording head applies a magnetic charge, aligning the particles in either a north
or south direction, corresponding to the 0s and 1s of the digital data. On playback, a laser beam
set at a lower temperature is aimed at the MD. The shiny surface of the MD reflects the laser
light into a sensor. The differently aligned magnetic particles reflect the laser light in different


                                                [5]
ways, and the sensor converts the changes into a digital code. A computer uses the digital code to
reconstruct the sound that was originally recorded




HARD DISK




The inside of a computer hard disk drive consists of four main components. The
round disk platter is usuall y made of aluminum, glass, o r ceramic and is coated
with a magnetic media that contains all the data stored on the hard drive. The
yellow arm like device that extends over the disk platter is known as the head
arm and is the device that reads the information off of the disk platter. The head
arm is attached to the head actuator, which controls the head arm. Not shown is
the chassis which encases and holds all the hard disk drive components.


Memory stored on external magnetic media includes magnetic tape, a hard disk,
and a floppy disk. Magnetic tape is a form of external computer memory used

                                               [6]
primaril y for backup storage. Like the surface on a magnetic disk, the surface of
tape is coated with a material that can be magnetized. As the tape passes over an
electromagnet, individual bits are magneticall y encoded. Computer systems
using magnetic tape storage devices employ machinery similar to that used with
analog tape: open -reel tapes, cassette tapes, and helical -scan tapes (similar to




video tape).


Another form of magnetic memory uses a spinning disk coated with magnetic
material. As the disk spins, a sensitive electromagnetic sensor, called a read -
write head, scans across the surface of the disk, reading and writing magnetic
spots in concentric circles called tracks.


Magnetic disks a re classified as either hard or floppy, depending on the
flexibilit y of the material from which they are made. A floppy disk is made of
flexible plastic with small pieces of a magnetic material imbedded in its surface.
The read-write head touches the surfa ce of the disk as it scans the floppy. A
hard disk is made of a rigid metal, with the read -write head flying just above its
surface on a cushion of air to prevent wear.


Disk Drive, in computer science, a device that reads or writes data, or both, on a
disk medium. The disk medium may be either magnetic, as with floppy disks or
hard disks; optical, as with CD -ROM (compact disc -read onl y memory) disks; or
a combination of the two, as with magneto -optical disks. Nearl y all computers
come equipped with drives f or these t ypes of disks, and the drives are usuall y
inside the computer, but may also be connected as external, or peripheral,
devices.



                                         [7]
The main components of a disk drive are the motor, which rotates the disk; the
read-write mechanism; and the logic board , which receives commands from the
operating system to place or retrieve information on the disk. To read or write
information to a disk, drives use various methods. Floppy and hard drives use a
small magnetic head to magnetize portions of the disk surface , CD-ROM and
WORM (Write-Once-Read-Many) drives use lasers to read information, and
magneto-optical drives use a combination of magnetic and optical techniques to
store and retrieve information.




Floppy and hard disk drives store information on magnetic di sks. The disk itself
is a thin, flexible piece of plastic with tiny magnetic particles imbedded in its
surface. To write data to the disk, the read -write head creates a small magnetic
field that aligns the magnetic poles of the particles on the surface of the disk
directl y beneath the head. Particles aligned in one direction represent a 0 while
particles aligned in the opposite direction represent a 1. To read data from a
disk, the drive head scans the surface of the disk. The magnetic fields of the
particles in the disk induce an alternating electric current in the read -write head,
which is then translated into the series of 1s and 0s that the computer
understands.


THE PLATTERS

The platters are actual disks inside the drive that store the magnetized data.
Traditionall y platters are made up of alight aluminum alloy and coated with
magneticall y material such as a ferrite compound that is applied in liquid form
and spun evenl y across the platter or thin metal film plating that is applied to
the platter through electroplating, the same way chrome is produced. Most
drives have at least 2 platters and the larger the storage capacit y of the drive,
the more platters there are.
                                         [8]
THE SPINDLE MOTOR

The platters in a drive are separated by disk spacers and are clamped to a
rotating spindle that turns all the platters in unison. The spindle motor is build
right into the spindle or mounted directly below it and spins the platters at a
constant set range ranging from 3600 to 7200 RPM. The motor is attached to the
feedback loop to ensure that it spins at precisel y the speed it is supposed to.




THE READ/WRITE HEADS

The read/write heads read and write data to the platters. There is t ypicall y one
head per platter side, and each head is attached to a single actuator shaft so that
all the head move in unison. When one head is over a track, all the other heads
are at same location over their respective surfaces. Typically, onl y one of the
heads is active at a time, i.e., reading or writing data. When not in use, the
heads rest o n the stationary platters, but when in motion the spinning of the
platters create air pressure that lifts the heads off the platters. The space
between the platter and the head is so minute that even one dust particle or a
fingerprint could disable the spi n. This necessitates that the hard drive assembl y
be done in clean room. When the platters cease spinning the heads come to rest,
or park, at a predetermined position on the heads, called the landing zone.


THE HEAD ACTUATOR

All the heads are attached to a single head actuator arm that moves the heads
around the platters. Older hard drives used a stepper motor actuator, which
moved the heads based on a motor reacting to stepper pulses. Each pulse moved
the actuator over the platters in predefined steps. St epper motor actuators are
not used in modern drives because they are prone to alignment problems and are

                                         [9]
highl y sensitive to heat. Modern hard drives use a voice coil actuator, which
controls the movement of a coil toward or away from a permanent magnet ba sed
on the amount of current flowing through it. This guidance system is called a
servo.


The platters, spindle, spindle motor, head actuator and the read/write heads are
all contained in a chamber called the head dish assembl y (HDA). Outside of the
HAD is the logic board that controls the movements of data into and out of the
drive.




FLOPPY DISK
Floppy Disk, in computer science, a round, flat piece of Mylar coated with
ferric oxide, rust like substance containing tiny particles capable of holding a
magnetic field, and encased in a protective plastic cover, the disk jacket. Data is
stored on a floppy disk by the disk drive's read/write head, which alters the
magnetic orientation of the particles. Orientation in one direction represents
binary 1; orientation in the other, binary 0. Typicall y, a floppy disk is 5.25
inches in diameter, with a large hole in the center that fits around the spindle in
the disk drive. Depending on its capacit y, such a disk can hold from a few
hundred thousand to over one million bytes of data. A 3.5 -inch disk encased in
rigid plastic is usually called a microfloppy disk but can also be called a floppy
disk


MOTHERBOARD




                                       [10]
Motherboard, in computer science, the main circuit board in a computer. The
most important computer chips and other electronic components that give
function to a computer are located on the motherboard. The motherboard is a
printed circuit board that connects the various elements on it through the use of




traces, or electrical pathways. The motherboard contains the connectors for
attaching additional boards. The motherboard contains the CPU, BIOS, memory
mass storage interfaces, serial and parallel ports, expansion slots and all the
controllers required to control standard peripheral devices, such as display
screen, keyboard, mouse and disk drive. Collectivel y all these chips that reside
on the motherboard are known as motherboard chipset. The motherboard is a
central element of the personal computer, the main circuit board to which one
connects memory, peripheral s and other devices, which extend the capabilities
of the computer. The motherboard is indispensable to the computer and provides
the main computing capabilit y.


Personal computers normall y have one central processing unit (CPU), or
microprocessor, which is located with other chips on the motherboard. The
manufacturer and model of the CPU chip carried by the motherboard is a key
                                       [11]
criterion for designating the speed and other capabilities of the computer. The
CPU    in   many   personal   computers    is    not   permanentl y   a ttached   to   the
motherboard, but is instead plugged into a socket so that it may be removed and
upgraded.


Motherboards also contain important computing components, such as the basic
input/output system (BIOS), which contains the basic set of instructions
required to control the computer when it is first turned on; different t ypes of
memory chips such as random access memory (RAM) and cache memory; mouse,
keyboard, and monitor control circuitry; and logic chips that control various
parts of the computer‘s fun ction. Having as many of the key components of the
computer as possible on the motherboard improves the speed and operation of
the computer.


Users may expand their computer‘s capabilit y by inserting an expansion board
into special expansion slots on the mo therboard. Expansion slots are standard




with nearl y all personal computers and offer faster speed, better graphics
capabilities, communication capabilit y with other computers, and audio and
video capabilities. Expansion slots come in either half or full size, and can
transfer 8 or 16 bits (the smallest units of information that a computer can
process) at a time, respectivel y.


The pathways that carry data on the motherboard are called buses. The amount
of data that can be transmitted at one time between a device, such as a printer or
monitor, and the CPU affects the speed at which programs run. For this reason,
buses are designed to carry as much data as possible. To work properl y,
expansion boards must conform to bus standards such as integrated drive



                                          [12]
electronics (IDE), Extended Industry Standard Architecture (EISA), or small
computer system interface (SCS I).


MOUSE




A mouse is a pointing device that helps a user navigates through a graphical
computer interface. Connected to the computer by a c able, it is generall y
mapped so that an on -screen cursor may be controlled by moving the mouse
across a flat surface. Two common types of mouse, the Microsoft mouse
(bottom) and the Apple ADB (Apple Desktop Bus) mouse ( top) are shown here.


Mouse (computer), a common pointing device, popularized by its inclusion as




standard equipment with the Apple Macintosh. With the rise in popularit y of
graphical user interfaces (Graphical User Interface) in MS -DOS; UNIX, and
OS/2, use of mice is growing throughout the personal computer and workstation
worlds. The basic features of a mouse are a casing with a flat bottom, designed
to be gripped by one hand; one or more buttons on the top; a multidirectional
detection device (usuall y a ball) on the bottom; and a cable con necting the
mouse to the computer. See the illustration. By moving the mouse on a surface
(such as a desk), the user t ypicall y controls an on -screen cursor. A mouse is a
relative pointing device because there are no defined limits to the mouse's
movement and because its placement on a surface does not map directl y to a
                                       [13]
specific screen location. To select items or choose commands on the screen, the
user presses one of the mouse's buttons, producing a ―mouse click.


Bus Mouse, in computer science, a mouse that attaches to the computer's bus
through a special card or port rather than through a serial port. Mechanical
Mouse, in computer science, a t ype of mouse in which the motion of a ball on
the bottom of the mouse is translated into directional signals. As the user moves
the mouse, the ball t ypicall y spins a pair of wheels inside the mouse. These
conductive wheels might, in turn, rotate additional wheels via axles or gears. At
least one pair of wheels has conductive markings on their surface. Because the
markings permit an electric current to flow, a set of conductive brushes that ride
on the surface of the conductive wheels can detect the conductive markings. The
electronics in the mouse translate these electrical -movement signals into mouse -
movement informatio n that can be used by the computer.


OPTICAL MOUSE

Optical Mouse, in computer science, a type of mouse that uses a pair of light -
emitting diodes (LEDs) and a special reflective grid pad to detect motion. The
two lights are of different colors, and the sp ecial mouse pad has a grid of lines


in the same colors, one color for vertical lines and another for horizontal lines.
Light detectors paired with the LEDs sense when a colored light passes over a
line of the same color, indicating the direction of the m ovement. See also
Mechanical Mouse; Optomechanical Mouse; Pointing Device.


OPTOMECHANICAL MOUSE

As a mouse is moved, a ball in the mouse‘s interior is rolled. This motion turns
two axles, corresponding to the two dimensions of movement. Each axle spins a
slotted wheel. On one side of each wheel, a light -emitting diode (LED) sends a

                                        [14]
path of light through the slots to a receiving phototransistor on the other side.
The pattern of light to dark is then translated to an electrical signal, which
reports the mou se‘s position and speed and is reflected in the movement of the
cursor on the computer‘s screen.




Optomechanical Mouse, in computer science, a t ype of mouse in which motion




is translated into directional signals through a combination of optical and
mechanical means. The optical portion includes pairs of light -emitting diodes
(LEDs) and matching sensors; the mechanical portion consists of rotating
wheels with cutout slits. When the mouse is moved, the wheels turn and the
light from the LEDs either passes through the slits and strikes a light sensor or
is blocked by the solid portions of the wheels. These chan ges in light contact
are detected by the pairs of sensors and interpreted as indications of movement.
Because the sensors are slightl y out of phase with one another, the direction of


                                      [15]
movement is determined by which sensor is the first to regain light conta ct.
Because   it   uses   optical   equipment     instead   of   mechanical   parts,   an
optomechanical mouse eliminates the need for many of the wear -related repairs
and maintenance necessary with purel y mechanical mice, but it does not require
the special operating surface s associated with optic mice.


Serial Mouse, in computer science, a mouse that attaches to the computer
through a standard serial port of the type that can also be used for other
purposes, such as attaching a modem. If a serial port is unavailable or anoth er
serial port cannot be added to the system, however, a bus mouse, which uses its
own computer card, might be used instead.


TRACKBALL




A trackball is basicall y an inverted mouse; the user rotates the ball itself while
clicking nearby buttons. Trackball users argue the device is more efficient


because it is stationary and saves arm movement; however, many mouse users
are uncomfortable with the different style of input. Trackball, in computer
science, a popular pointing device that can be roughl y described as a mouse on
its back. A trackball consists of a ball resting on two rollers at right angles to
each other, which translate the ball's motion into vertical and horizontal
movement on the screen. A trackball also t ypicall y has one or more buttons to
initiate other actions. The onl y functional difference between a mechanical

                                       [16]
mouse and a trackball is in how the ba ll is moved: With a mouse, the ball is
rolled by moving the entire unit over a desktop or other surface; with a
trackball, the housing is stationary, and the ball is rolled with the hand. A
trackball is useful for fine work because the user can exert finge rtip control; a
mouse is better for bold moves, such as those used in navigating within a
graphical user interface. Another major advantage of a trackball is that i t takes
little desktop surface.




                                       [17]
                        PRACTICAL – 2

AIM :- Introduction with network computing
         A computer network is an interconnection of a group of computers. Networks may be
classified by what is called the network layer at which they operate according to basic reference
models considered as standards in the industry such as the four-layer Internet Protocol Suite
model. While the seven-layer Open Systems Interconnection (OSI) reference model is better
known in academia, the majority of networks use the Internet Protocol Suite (IP) as their network
model.

By scale

Computer networks may be classified according to the scale: Personal area network (PAN),
Local Area Network (LAN), Campus Area Network (CAN), Metropolitan area network (MAN),
or Wide area network (WAN). As Ethernet increasingly is the standard interface to networks,
these distinctions are more important to the network administrator than the end user. Network
administrators may have to tune the network, based on delay that derives from distance, to
achieve the desired Quality of Service (QoS). The primary difference in the networks is the size.

Controller Area Networks are a special niche, as in control of a vehicle's engine, a boat's
electronics, or a set of factory robots.

By connection method

Computer networks may be classified according to the hardware technology that is used to
connect the individual devices in the network such as Optical fiber, Ethernet, Wireless LAN,
HomePNA, or Power line communication.

Ethernets use physical wiring to connect devices. Often, they employ the use of hubs, switches,
bridges, and routers.

Wireless LAN technology is built to connect devices without wiring. These devices use a radio
frequency to connect.

                                              [18]
By functional relationship (Network Architectures)

Computer networks may be classified according to the functional relationships which exist
between the elements of the network, for example Active Networking, Client-server and Peer-to-
peer (workgroup) architectures.

By network topology

Computer networks may be classified according to the network topology upon which the
network is based, such as Bus network, Star network, Ring network, Mesh network, Star-bus
network, Tree or Hierarchical topology network, etc.

Network Topology signifies the way in which intelligent devices in the network see their logical
relations to one another. The use of the term "logical" here is significant. That is, network
topology is independent of the "physical" layout of the network. Even if networked computers
are physically placed in a linear arrangement, if they are connected via a hub, the network has a
Star topology, rather than a Bus Topology. In this regard the visual and operational
characteristics of a network are distinct; the logical network topology is not necessarily the same
as the physical layout.

By protocol

Computer networks may be classified according to the communications protocol that is being
used on the network. See the articles on List of network protocol stacks and List of network
protocols for more information. For a development of the foundations of protocol design see
Srikant 2004 [1] and Meyn 2007 [2]

Types of networks:

Below is a list of the most common types of computer networks in order of scale.

Personal Area Network (PAN)

A personal area network (PAN) is a computer network used for communication among computer
devices close to one person. Some examples of devices that may be used in a PAN are printers,
fax machines, telephones, PDAs or scanners. The reach of a PAN is typically within about 20-30
                                               [19]
feet (approximately 4-6 Meters). PANs can be used for communication among the individual
devices (intrapersonal communication), or for connecting to a higher level network and the
Internet (an uplink).

Personal area networks may be wired with computer buses such as USB and FireWire. A
wireless personal area network (WPAN) can also be made possible with network technologies
such as IrDA and Bluetooth.

Local Area Network (LAN)

A network covering a small geographic area, like a home, office, or building. Current LANs are
most likely to be based on Ethernet technology. For example, a library will have a wired or
wireless LAN for users to interconnect local devices (e.g., printers and servers) connect to the
internet. All of the PCs in the library are connected by category 5 (Cat5) cable, running the IEEE
802.3 protocol through a system of interconnection devices and eventually connect to the
internet. The cables to the servers are on Cat 5e enhanced cable, which will support IEEE 802.3
at 1 Gbps.

The staff computers (bright green) can get to the color printer, checkout records, and the
academic network and the Internet. All user computers can get to the Internet and the card
catalog. Each workgroup can get to its local printer. Note that the printers are not accessible from
outside their workgroup.

Typical library network, in a branching tree topology and controlled access to resources

All interconnect devices must understand the network layer (layer 3), because they are handling
multiple subnets (the different colors). Those inside the library, which have only 10/100 Mbps
Ethernet connections to the user device and a Gigabit Ethernet connection to the central router,
could be called "layer 3 switches" because they only have Ethernet interfaces and must
understand IP. It would be more correct to call them access routers, where the router at the top is
a distribution router that connects to the Internet and academic networks' customer access
routers.

Depending on the circumstance, the computers in the network might be connected using cables
and hubs. Other networks might be connected strictly wirelessly. It depends on the number of
                                               [20]
PCs that you are trying to connect, the physical layout of your workspace, and the various needs
of network. Not shown in this diagram, for example, is a wireless workstation used when
shelving books.

The defining characteristics of LANs, in contrast to WANs (wide area networks), include their
much higher data transfer rates, smaller geographic range, and lack of a need for leased
telecommunication lines. Current Ethernet or other IEEE 802.3 LAN technologies operate at
speeds up to 10 Gbit/s. This is the data transfer rate. IEEE has projects investigating the
standardization of 100 Gbit/s, and possibly 40 Gbit/s. Inverse multiplexing is commonly used to
build a faster aggregate from slower physical streams, such as bringing 4 Gbit/s aggregate stream
into a computer or network element with four 1 Gbit/s interfaces.

Campus Area Network (CAN)

A network that connects two or more LANs but that is limited to a specific and contiguous
geographical area such as a college campus, industrial complex, or a military base. A CAN, may
be considered a type of MAN (metropolitan area network), but is generally limited to an area that
is smaller than a typical MAN.

This term is most often used to discuss the implementation of networks for a contiguous area.
For Ethernet based networks in the past, when layer 2 switching (i.e., bridging (networking) was
cheaper than routing, campuses were good candidates for layer 2 networks, until they grew to
very large size. Today, a campus may use a mixture of routing and bridging. The network
elements used, called "campus switches", tend to be optimized to have many Ethernet-family
(i.e., IEEE 802.3) interfaces rather than an arbitrary mixture of Ethernet and WAN interfaces.

Metropolitan Area Network (MAN)

A Metropolitan Area Network is a network that connects two or more Local Area Networks or
Campus Area Networks together but does not extend beyond the boundaries of the immediate
town, city, or metropolitan area. Multiple routers, switches & hubs are connected to create a
MAN.

Wide Area Network (WAN)


                                              [21]
A WAN is a data communications network that covers a relatively broad geographic area (i.e.
one city to another and one country to another country) and that often uses transmission facilities
provided by common carriers, such as telephone companies. WAN technologies generally
function at the lower three layers of the OSI reference model: the physical layer, the data link
layer, and the network layer.

Global Area Network (GAN)

Global area networks (GAN) specifications are in development by several groups, and there is no
common definition. In general, however, a GAN is a model for supporting mobile
communications across an arbitrary number of wireless LANs, satellite coverage areas, etc. The
key challenge in mobile communications is "handing off" the user communications from one
local coverage area to the next. In IEEE Project 802, this involves a succession of terrestrial
                                        [3]
Wireless local area networks (WLAN)           . INMARSAT has defined a satellite-based Broadband
Global Area Network (BGAN).

IEEE mobility efforts focus on the data link layer and make assumptions about the media.
Mobile IP is a network layer technique, developed by the IETF, which is independent of the
media type and can run over different media while still keeping the connection.

Internetwork

Two or more networks or network segments connected using devices that operate at layer 3 (the
'network' layer) of the OSI Basic Reference Model, such as a router. Any interconnection among
or between public, private, commercial, industrial, or governmental networks may also be
defined as an internetwork.

In modern practice, the interconnected networks use the Internet Protocol. There are at least three
variants of internetwork, depending on who administers and who participates in them:

      Intranet
      Extranet
      "The" Internet




                                                  [22]
Intranets and extranets may or may not have connections to the Internet. If connected to the
Internet, the intranet or extranet is normally protected from being accessed from the Internet
without proper authorization. The Internet itself is not considered to be a part of the intranet or
extranet, although the Internet may serve as a portal for access to portions of an extranet.


Intranet

An intranet is a set of interconnected networks, using the Internet Protocol and uses IP-based
tools such as web browsers, that is under the control of a single administrative entity. That
administrative entity closes the intranet to the rest of the world, and allows only specific users.
Most commonly, an intranet is the internal network of a company or other enterprise.


Extranet

An extranet is a network or internetwork that is limited in scope to a single organization or
entity but which also has limited connections to the networks of one or more other usually, but
not necessarily, trusted organizations or entities (e.g. a company's customers may be given
access to some part of its intranet creating in this way an extranet, while at the same time the
customers may not be considered 'trusted' from a security standpoint). Technically, an extranet
may also be categorized as a CAN, MAN, WAN, or other type of network, although, by
definition, an extranet cannot consist of a single LAN; it must have at least one connection with
an external network.


Internet

A specific internetwork , consisting of a worldwide interconnection of governmental, academic,
public, and private networks based upon the Advanced Research Projects Agency Network
(ARPANET) developed by ARPA of the U.S. Department of Defense – also home to the World
Wide Web (WWW) and referred to as the 'Internet' with a capital 'I' to distinguish it from other
generic internetworks.

Participants in the Internet, or their service providers, use IP Addresses obtained from address
registries that control assignments. Service providers and large enterprises also exchange


                                                [23]
information on the reachability of their address ranges through the BGP Border Gateway
Protocol.




                                         [24]
                         PRACTICAL – 3
AIM: - Introduction to client-server, peer to peer, direct
cable connection networks.

CLENT-SERVER
Client-server is a computing architecture which separates a client from a server, and is almost
always implemented over a computer network. Each client or server connected to a network can
also be referred to as a node. The most basic type of client-server architecture employs only two
types of nodes: clients and servers. This type of architecture is sometimes referred to as two-tier.
It allows devices to share files and resources.

Each instance of the client software can send data requests to one or more connected servers. In
turn, the servers can accept these requests, process them, and return the requested information to
the client. Although this concept can be applied for a variety of reasons to many different kinds
of applications, the architecture remains fundamentally the same.

The interaction between client and server is often described using sequence diagrams. Sequence
diagrams are standardized in the Unified Modeling Language.


Characteristics of a client
      Request sender is known as client
      Initiates requests
      Waits for and receives replies.
      Usually connects to a small number of servers at one time
      Typically interacts directly with end-users using a graphical user interface


Characteristics of a server

      Receiver of request which is sent by client is known as server
      Passive (slave)
      Waits for requests from clients
      Upon receipt of requests, processes them and then serves replies
                                              [25]
       Usually accepts connections from a large number of clients




       Typically does not interact directly with end-users


Multi-tiered architecture
Some designs are more sophisticated and consist of three different kinds of nodes: clients,
application servers which process data for the clients, and database servers which store data for
the application servers. This configuration is called a three-tier architecture, and is the most
commonly used type of client-server architecture. Designs that contain more than two tiers are
referred to as multi-tiered or n-tiered.

The advantages of n-tiered architectures is that they are far more scalable, since they balance and
distribute the processing load among multiple, often redundant, specialized server nodes. This in
turn improves overall system performance and reliability, since more of the processing load can
be accommodated simultaneously.[1]

The disadvantages of n-tiered architectures include:

    1. More load on the network itself, due to a greater amount of network traffic.
    2. More difficult to program and test than in two-tier architectures because more devices
        have to communicate in order to complete a client's request.


Advantages
       In most cases, a client-server architecture enables the roles and responsibilities of a
        computing system to be distributed among several independent computers that are known
        to each other only through a network. This creates an additional advantage to this
        architecture: greater ease of maintenance. For example, it is possible to replace, repair,
        upgrade, or even relocate a server while its clients remain both unaware and unaffected
        by that change. This independence from change is also referred to as encapsulation.
       All the data is stored on the servers, which generally have far greater security controls
        than most clients. Servers can better control access and resources, to guarantee that only
        those clients with the appropriate permissions may access and change data.
                                               [26]
      Since data storage is centralized, updates to those data are far easier to administer than
       would be possible under a P2P paradigm. Under a P2P architecture, data updates may




       need to be distributed and applied to each "peer" in the network, which is both time-
       consuming and error-prone, as there can be thousands or even millions of peers.

      Many mature client-server technologies are already available which were designed to
       ensure security, 'friendliness' of the user interface, and ease of use.
      It functions with multiple different clients of different capabilities.


Disadvantages
      Traffic congestion on the network has been an issue since the inception of the client-
       server paradigm. As the number of simultaneous client requests to a given server
       increases, the server can become severely overloaded. Contrast that to a P2P network,
       where its bandwidth actually increases as more nodes are added, since the P2P network's
       overall bandwidth can be roughly computed as the sum of the bandwidths of every node
       in that network.
      The client-server paradigm lacks the robustness of a good P2P network. Under client-
       server, should a critical server fail, clients‘ requests cannot be fulfilled. In P2P networks,
       resources are usually distributed among many nodes. Even if one or more nodes depart
       and abandon a downloading file, for example, the remaining nodes should still have the
       data needed to complete the download.


Examples
       Imagine you are visiting an e-commerce web site. In this case, your computer and web
browser would be considered the client, while the computers, databases, and applications that
make up the online store would be considered the server. When your web browser requests
specific information from the online store, the server finds all of the data in the database needed
to satisfy the browser's request, assembles that data into a web page, and transmits that page back
to your web browser for you to view.


                                                [27]
Specific types of clients include web browsers, email clients, and online chat clients. Specific
types of servers include web servers, ftp servers, application servers, database servers, mail
servers, file servers, print servers, and terminal servers. Most web services are also types of
servers.




PEER TO PEER
A peer-to-peer (or "P2P", or, rarely, "PtP") computer network uses diverse connectivity
between participants in a network and the cumulative bandwidth of network participants rather
than conventional centralized resources where a relatively low number of servers provide the
core value to a service or application. Peer-to-peer networks are typically used for connecting
nodes via largely ad hoc connections. Such networks are useful for many purposes. Sharing
content files (see file sharing) containing audio, video, data or anything in digital format is very
common, and realtime data, such as telephony traffic, is also passed using P2P technology.

A pure peer-to-peer network does not have the notion of clients or servers, but only equal peer
nodes that simultaneously function as both "clients" and "servers" to the other nodes on the
network. This model of network arrangement differs from the client-server model where
communication is usually to and from a central server. A typical example for a non peer-to-peer
file transfer is an FTP server where the client and server programs are quite distinct, and the
clients initiate the download/uploads and the servers react to and satisfy these requests.

The earliest peer-to-peer network in widespread use was the Usenet news server system, in
which peers communicated with one another to propagate Usenet news articles over the entire
Usenet network. Particularly in the earlier days of Usenet, UUCP was used to extend even
beyond the Internet. However, the news server system also acted in a client-server form when
individual users accessed a local news server to read and post articles. The same consideration
applies to SMTP email in the sense that the core email relaying network of Mail transfer agents
is a peer-to-peer network while the periphery of Mail user agents and their direct connections is
client server.

Some networks and channels such as Napster, OpenNAP and IRC server channels use a client-
server structure for some tasks (e.g. searching) and a peer-to-peer structure for others. Networks
                                                [28]
such as Gnutella or Freenet use a peer-to-peer structure for all purposes, and are sometimes
referred to as true peer-to-peer networks, although Gnutella is greatly facilitated by directory
servers that inform peers of the network addresses of other peers.

Peer-to-peer architecture embodies one of the key technical concepts of the Internet, described in
the first Internet Request for Comments, RFC 1, "Host Software" dated 7 April 1969. More




recently, the concept has achieved recognition in the general public in the context of the absence
of central indexing servers in architectures used for exchanging multimedia files.

The concept of peer to peer is increasingly evolving to an expanded usage as the relational
dynamic active in distributed networks, i.e. not just computer to computer, but human to human.
Yochai Benkler has coined the term "commons-based peer production" to denote collaborative
projects such as free software. Associated with peer production are the concept of peer
governance (referring to the manner in which peer production projects are managed) and peer
property (referring to the new type of licenses which recognize individual authorship but not
exclusive property rights, such as the GNU General Public License and the Creative Commons
licenses).


Classifications of peer-to-peer networks
Peer-to-peer networks can be classified by what they can be used for:

       file sharing
       telephony
       media streaming (radio, video)
       discussion forums

Other classification of peer-to-peer networks is according to their degree of centralization.

In 'pure' peer-to-peer networks:

       Peers act as equals, merging the roles of clients and server
       There is no central server managing the network
       There is no central router
                                                [29]
Some examples of pure peer-to-peer application layer networks designed for file sharing are
Gnutella and Freenet.

There also exist countless hybrid peer-to-peer systems:

          Has a central server that keeps information on peers and responds to requests for that
           information.
          Peers are responsible for hosting available resources (as the central server does not have
           them), for letting the central server know what resources they want to share, and for
           making its shareable resources available to peers that request it.
          Route terminals are used addresses, which are referenced by a set of indices to obtain an
           absolute address.

e.g.

          Centralized P2P network such as Napster
          Decentralized P2P network such as KaZaA
          Structured P2P network such as CAN
          Unstructured P2P network such as Gnutella
          Hybrid P2P network (Centralized and Decentralized) such as JXTA, GreenTea and
           Shwup


Advantages of peer-to-peer networks
An important goal in peer-to-peer networks is that all clients provide resources, including
bandwidth, storage space, and computing power. Thus, as nodes arrive and demand on the
system increases, the total capacity of the system also increases. This is not true of a client-server
architecture with a fixed set of servers, in which adding more clients could mean slower data
transfer for all users.

The distributed nature of peer-to-peer networks also increases robustness in case of failures by
replicating data over multiple peers, and -- in pure P2P systems -- by enabling peers to find the
data without relying on a centralized index server. In the latter case, there is no single point of
failure in the system.



                                                   [30]
When the term peer-to-peer was used to describe the Napster network, it implied that the peer
protocol was important, but, in reality, the great achievement of Napster was the empowerment
of the peers (i.e., the fringes of the network) in association with a central index, which made it
fast and efficient to locate available content. The peer protocol was just a common way to
achieve this. While the original Napster network was a P2P network, the newest version of
Napster has no connection to P2P networking at all. The modern day version of Napster is a
subscription based service which allows you to download music files legally.


Unstructured and structured P2P networks
The P2P overlay network consists of all the participating peers as network nodes. There are links
between any two nodes that know each other: i.e. if a participating peer knows the location of
another peer in the P2P network, then there is a directed edge from the former node to the latter
in the overlay network. Based on how the nodes in the overlay network are linked to each other,
we can classify the P2P networks as unstructured or structured.

An unstructured P2P network is formed when the overlay links are established arbitrarily. Such
networks can be easily constructed as a new peer that wants to join the network can copy
existing links of another node and then form its own links over time. In an unstructured P2P
network, if a peer wants to find a desired piece of data in the network, the query has to be
flooded through the network to find as many peers as possible that share the data. The main
disadvantage with such networks is that the queries may not always be resolved. Popular content
is likely to be available at several peers and any peer searching for it is likely to find the same
thing, but if a peer is looking for rare data shared by only a few other peers, then it is highly
unlikely that search will be successful. Since there is no correlation between a peer and the
content managed by it, there is no guarantee that flooding will find a peer that has the desired
data. Flooding also causes a high amount of signalling traffic in the network and hence such
networks typically have very poor search efficiency. Most of the popular P2P networks such as
Gnutella and FastTrack are unstructured.

Structured P2P network employ a globally consistent protocol to ensure that any node can
efficiently route a search to some peer that has the desired file, even if the file is extremely rare.
Such a guarantee necessitates a more structured pattern of overlay links. By far the most
common type of structured P2P network is the distributed hash table (DHT), in which a variant
of consistent hashing is used to assign ownership of each file to a particular peer, in a way
analogous to a traditional hash table's assignment of each key to a particular array slot. Some
well known DHTs are Chord, Pastry, Tapestry, CAN, and Tulip. Not a DHT-approach but a
structured P2P network is HyperCuP.




Comparison to Peer-to-Peer Architecture

                                                [31]
Another type of network architecture is known as peer-to-peer, because each node or instance of
the program can simultaneously act as both a client and a server, and because each has
equivalent responsibilities and status. Peer-to-peer architectures are often abbreviated using the
acronym P2P.

Both client-server and P2P architectures are in wide usage today.




Direct cable connection
Direct Cable Connection (DCC), is a feature of Microsoft Windows that allows a computer to
transfer and share files (or connected printers) with another computer, via a connection using
either the serial port, parallel port or the infrared port of each computer. It is well-suited for
computers that do not have an ethernet adapter installed, although DCC in Windows XP can be
configured to use one (with a proper crossover cable if no network hub is used) if available.


DCC with Serial Port

If using the serial ports of the computer, a null modem cable (or a null modem adapter connected
to a standard serial cable) must be used to connect each of the two computers to communicate
properly.


DCC with Parallel Port

If the parallel ports are used, Windows supports standard or basic 4-bit cable (commonly known
as LapLink cable), Enhanced Capabilities Port (ECP) cable, or Universal Cable Module (UCM)
cable (which was known as DirectParallel cable by Parallel Technologies).


DCC with IR

Infrared communication ports, like the ones found on laptop computers (such as IrDA), can also
be used.

DCC with USB

Connecting any two computers using USB requires a special proprietary bridge cable solution;
the usual USB-to-USB cable does not work as USB does not support such type of
                                               [32]
communication and attempting to do so may even damage the connecting computers as it can
short the two computers' power supplies together, possibly destroying one or both machines or
causing a fire hazard. Therefore, Direct Cable Connection over USB is not possible; a USB link
cable must be used, as seen in the Microsoft knowledge base article 814982 shows.

Windows Vista drops support for the Direct cable connection feature as ethernet, Wi-Fi and
Bluetooth have become ubiquitous on current generation computers. To transfer files and
settings, Windows Vista includes Windows Easy Transfer, which uses a proprietary USB-to-
USB bridge cable made by Belkin.




                                             [33]
                     PRACTICAL – 4
AIM: - Study of LAN components and it’s various topologies


Basic LAN components




There are essentially five basic components of a LAN

Network Devices such as Workstations, Printers, File Servers which are normally accessed by
all other computers

Network Communication Devices i.e. devices such as hubs, routers, switches etc., used for
network operations

Network Interface Cards (NICs) for each network device required to access the network .

Cable as a physical transmission medium.

Network Operating System - software applications required to control the use of the network
LAN standards.




                                             [34]
All networks are made up of basic hardware building blocks to interconnect network nodes, such
as Network Interface Cards (NICs), Bridges, Hubs, Switches, and Routers. In addition, some
method of connecting these building blocks is required, usually in the form of galvanic cable
(most commonly Category 5 cable). Less common are microwave links (as in IEEE 802.11) or
optical cable ("optical fiber").

Network Interface Cards

A network card, network adapter or NIC (network interface card) is a piece of computer
hardware designed to allow computers to communicate over a computer network. It provides
physical access to a networking medium and often provides a low-level addressing system
through the use of MAC addresses. It allows users to connect to each other either by using cables
or wirelessly.

Repeaters

A repeater is an electronic device that receives a signal and retransmits it at a higher level or
higher power, or onto the other side of an obstruction, so that the signal can cover longer
distances without degradation.

Because repeaters work with the actual physical signal, and do not attempt to interpret the data
being transmitted, they operate on the Physical layer, the first layer of the OSI model.

Hubs

A hub contains multiple ports. When a packet arrives at one port, it is copied to all the ports of
the hub. When the packets are copied, the destination address in the frame does not change to a
broadcast address. It does this in a rudimentary way, it simply copies the data to all of the Nodes
connected to the hub. [4]

Bridges

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 learns which MAC
addresses are reachable through specific ports. Once the bridge associates a port and an address,

                                               [35]
it will send traffic for that address only to that port. Bridges do send broadcasts to all ports
except the one on which the broadcast was received.

Bridges learn the association of ports and addresses by examining the source address of frames
that it sees on various ports. Once a frame arrives through a port, its source address is stored and
the bridge assumes that MAC address is associated with that port. The first time that a previously
unknown destination address is seen, the bridge will forward the frame to all ports other than the
one on which the frame arrived.

Bridges come in three basic types:

   1. Local bridges: Directly connect local area networks (LANs)
   2. Remote bridges: Can be used to create a wide area network (WAN) link between LANs.
       Remote bridges, where the connecting link is slower than the end networks, largely have
       been replaced by routers.
   3. Wireless bridges: Can be used to join LANs or connect remote stations to LANs.

Switches

Switches are a marketing term that encompasses routers and bridges, as well as devices that may
distribute traffic on load or by application content (e.g., a Web URL identifier). Switches may
operate at one or more OSI layers, including physical, data link, network, or transport (i.e., end-
to-end). A device that operates simultaneously at more than one of these layers is called a
multilayer switch.

Overemphasizing the ill-defined term "switch" often leads to confusion when first trying to
understand networking. Many experienced network designers and operators recommend starting
with the logic of devices dealing with only one protocol level, not all of which are covered by
OSI. Multilayer device selection is an advanced topic that may lead to selecting particular
implementations, but multilayer switching is simply not a real-world design concept.

Routers

Routers are the networking device that forward data packets along networks by using headers
and forwarding tables to determine the best path to forward the packets. Routers work at the

                                               [36]
network layer of the TCP/IP model or layer 3 of the OSI model. Routers also provide
interconnectivity between like and unlike media (RFC 1812) This is accomplished by examining
the Header of a data packet, and making a decision on the next hop to which it should be sent
(RFC 1812) They use preconfigured static routes, status of their hardware interfaces, and routing
protocols to select the best route between any two subnets. A router is connected to at least two
networks, commonly two LANs or WANs or a LAN and its ISP's network. Some DSL and cable
modems, for home use, have been integrated with routers to allow multiple home computers to
access the Internet.




What is a Topology?

The physical topology of a network refers to the configuration of cables, computers, and
other peripherals. Physical topology should not be confused with logical topology which
is the method used to pass information between workstations.


Main Types of Physical Topologies

Linear Bus

A linear bus topology consists of a main run of cable with a terminator at each end (See
fig. 1). All nodes (file server, workstations, and peripherals) are connected to the linear
cable. Ethernet and LocalTalk networks use a linear bus topology.




                                      Fig. 1. Linear Bus topology

       Advantages of a Linear Bus Topology

              Easy to connect a computer or peripheral to a linear bus.
              Requires less cable length than a star topology.

                                                 [37]
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.
      Difficult to identify the problem if the entire network shuts down.
      Not meant to be used as a stand-alone solution in a large building.


Star
A star topology is designed with each node (file server, workstations, and
peripherals) connected directly to a central network hub or concentrator .Data on
a star network passes through the hub or concentrator before continuing to its
destination. The hub or concentrator manages and controls all functions of the
network. It also acts as a repeater for the data flow. This configuration is common
with twisted pair cable; however, it can also be used with coaxial cable or fiber
optic cable.




                                   Fig. 2. Star topology

Advantages of a Star Topology

      Easy to install and wire.
      No disruptions to the network then connecting or removing devices.
      Easy to detect faults and to remove parts.


Disadvantages of a Star Topology

                                          [38]
      Requires more cable length than a linear topology.
      If the hub or concentrator fails, nodes attached are disabled.
      More expensive than linear bus topologies because of the cost of the
       concentrators.

The protocols used with star configurations are usually Ethernet or LocalTalk.
Token Ring uses a similar topology, called the star-wired ring.


Star-Wired Ring
A star-wired ring topology may appear (externally) to be the same as a star
topology. Internally, the MAU (multistation access unit) of a star-wired ring
contains wiring that allows information to pass from one device to another in a
circle or ring (See fig. 3). The Token Ring protocol uses a star-wired ring
topology.


Tree
A tree topology combines characteristics of linear bus and star topologies. It
consists of groups of star-configured workstations connected to a linear bus
backbone cable (See fig. 4). Tree topologies allow for the expansion of an
existing network, and enable schools to configure a network to meet their needs.




                                Fig. 4. Tree topology

Advantages of a Tree Topology
                                        [39]
      Point-to-point wiring for individual segments.
      Supported by several hardware and software venders.




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.
      More difficult to configure and wire than other topologies.


5-4-3 Rule

A consideration in setting up a tree topology using Ethernet protocol is the 5-4-3
rule. One aspect of the Ethernet protocol requires that a signal sent out on the
network cable reach every part of the network within a specified length of time.
Each concentrator or repeater that a signal goes through adds a small amount of
time. This leads to the rule that between any two nodes on the network there can
only be a maximum of 5 segments, connected through 4 repeaters/concentrators.
In addition, only 3 of the segments may be populated (trunk) segments if they are
made of coaxial cable. A populated segment is one which has one or more nodes
attached to it . In Figure 4, the 5-4-3 rule is adhered to. The furthest two nodes on
the network have 4 segments and 3 repeaters/concentrators between them.


Considerations When Choosing a Topology:
      Money. A linear bus network may be the least expensive way to install a
       network; you do not have to purchase concentrators.
      Length of cable needed. The linear bus network uses shorter lengths of
       cable.
      Future growth. With a star topology, expanding a network is easily done
       by adding another concentrator.
      Cable type. The most common cable in schools is unshielded twisted pair,
       which is most often used with star topologies.



                                        [40]
Summary Chart:



       Physical     Common         Common
       Topology     Cable          Protocol

                    Twisted Pair
                                   Ethernet
       Linear Bus   Coaxial
                                   LocalTalk
                    Fiber

                    Twisted Pair   Ethernet
       Star
                    Fiber          LocalTalk

       Star-Wired
                    Twisted Pair   Token Ring
       Ring

                    Twisted Pair
       Tree         Coaxial        Ethernet
                    Fiber




                         [41]
                                      Practical – 5

Install and configure a network interface card in a workstation
Safety Precautions:

1. To prevent static electricity from damaging vital components of your computer, remember to
always attach an anti-static strip bracelet from your wrist to your computer case.
2. Computer cases were not meant to be opened by the everyday user and thus are not made with
the safety of the user in mind. Be careful for sharp edges in the casing that can cut your fingers
and/or hands.
3. Never remove a component or open a computer case while the power is on and the power
cable attached. Always remove all connecting cables before opening your case.


Opening the Case:


1. Shut off the system if it is on.
2. Remove all cables connecting to the computer.
3. Locate the screws holding the case cover in place on the frame.
4. Remove the screws attaching the cover to the frame.
5. Many new systems have tight cases and/or special cases. Removing the casing might require
some prying. Use a flat-head screwdriver to push the case open against the front panel. Seek
assistance if you cannot open the case alone. If the case seems really peculiar. Check your
computer's user manual first to see if they instruct you on how to open your computer.


Locating the Expansion Slots:


1. Place the open computer frame on its side with the motherboard facing up. This means you
can see the motherboard from a bird's eye view. The motherboard is the biggest board you can
see within the frame. It usually covers an entire side and has other smaller boards sticking up
from it.
2. Looking at the motherboard, try to locate the expansion slots. Expansion slots are either long

                                                [42]
black strips or short white strips that look like Lego blocks standing up. ISA slots are black. PCI
slots are white. Open slots are those that do not have other boards inserted in them.


Installing Your New Card:


1. Determine which interface (ISA or PCI) your card uses. ISA is long and the gold contacts are
large. PCI is much shorter and smaller.
2. Next, check to see if the expansion slot opening next to the slot is covered. If it is, remove the
cover by unscrewing it from the frame or popping it out. (IMPORTANT: Keep the screw and the
slot cover.) If you have a new case that has slot covers built in you will have to remove them
manually with a screwdriver. Please refer to your user manual for details.
3. When the slot cover has been removed, insert your card into the expansion slot on the
motherboard. Press firmly so the entire part of the card that has the gold contacts goes
completely into the expansion slot on the motherboard and will go no further. Do not use any
tools to try to hammer the card in if it does not fit.
4. Make sure the side of the card resembling the expansion slot cover you just removed is
covering most of the open slot.
5. Screw the card into place with the screw you removed from the expansion slot cover or a new
screw.


Replacing the Case:


1. After confirming the proper placement of the card, make sure you did not leave any tools or
screws within the computer. Replace the case and screw it back in place.
2. Reconnect all the cables to their proper places.


Booting Up:


1. Turn on the power.
2. Refer to your user's manual to install the proper drivers from the disk(s) that came with the
card.
3. Refer to the section setting up and configuring your computer for ResNet for the settings you
will need to access ResNet
                                                  [43]
Configuring your Network Interface Card:


Network TCP/IP Configuration for Windows 95-98
Double click the My Computer icon on your desktop.
Locate and double click on the Control Panel icon.
Next double click the Network icon to open the Network Control Panel.


Confirm Installation of your Ethernet Adapter Card:


The Local Area Connection window will list the Network Adapters, Network Protocols, and
Network Clients that you have installed on your system. The specific configuration will likely
vary from the illustration below.


If TCP/IP is already installed, it will appear in the list of installed protocols. Click once on the
listed item Internet Protocol (TCP/IP) - this will select this item. Now click the Properties
button.


Verify both the Obtain an IP address automatically and the Obtain DNS server address
automatically radio buttons are selected. Click on the Advanced button.


In the Advanced TCP/IP Settings window, click on the DNS tab. Uncheck the box Register this
connection's addresses in DNS toward the bottom of the screen.


Click OK to close the Advanced TCP/IP Settings window. Click OK to close the Internet
Protocol (TCP/IP) Properties window. Continue by clicking the OK button to close the Local
Area Connection Properties window. Close the Network and Dial-up Connections window.


Once you installed a new network card, windows will detect t he card, it will
first display a message like:

                                                 [44]
―PCI Ethernet card detected‖ and then it depends, whether your version of
windows knows already the t ype of network card:




Windows identified the network card and has a driver for i t in its own library: It
will start installing immediatel y the driver and other network components


Windows could not identify the network card and does not have a driver for it:
You are prompted to provide the floppy disk/ CD provided by the manufacturer
of the network card.


Open the propert y option in ‗My computer‘. Select the tab ‖Hardware‖, then
click in the section ―Device manager‖ on the button ―Device manager‖: look at

                                       [45]
―Network Adapters‖, click on the ―+‖ to display all installed adapters: now you
are ready to continue to configure your network.




                                      [46]
                              Practical – 6
AIM: - To Study different types of Cables used in networks
What is Network Cabling?

     Cable is the medium through which information usually moves from one network
     device to another. There are several types of cable which are commonly used with
     LANs. In some cases, a network will utilize only one type of cable, other
     networks will use a variety of cable types. The type of cable chosen for a network
     is related to the network's topology, protocol, and size. Understanding the
     characteristics of different types of cable and how they relate to other aspects of a
     network is necessary for the development of a successful network.




Unshielded Twisted Pair (UTP) Cable

     Twisted pair cabling comes in two varieties: shielded and unshielded. Unshielded
     twisted pair (UTP) is the most popular and is generally the best option for school
     networks (See fig. 1).




                                  Fig.1. Unshielded twisted pair




     The quality of UTP may vary from telephone-grade wire to extremely high-speed
     cable. The cable has four pairs of wires inside the jacket. Each pair is twisted with
     a different number of twists per inch to help eliminate interference from adjacent
     pairs and other electrical devices. The tighter the twisting, the higher the
     supported transmission rate and the greater the cost per foot. The EIA/TIA
     (Electronic Industry Association/Telecommunication Industry Association) has
     established standards of UTP and rated five categories of wire.
                                              [47]
                  Categories of Unshielded Twisted Pair


                 Type                          Use

               Category 1   Voice Only (Telephone Wire)

               Category 2   Data to 4 Mbps (LocalTalk)

               Category 3   Data to 10 Mbps (Ethernet)

               Category 4   Data to 20 Mbps (16 Mbps Token Ring)

               Category 5   Data to 100 Mbps (Fast Ethernet)


Buy the best cable you can afford; most schools purchase Category 3 or Category
5. If you are designing a 10 Mbps Ethernet network and are considering the cost
savings of buying Category 3 wire instead of Category 5, remember that the
Category 5 cable will provide more "room to grow" as transmission technologies
increase. Both Category 3 and Category 5 UTP have a maximum segment length
of 100 meters. In Florida, Category 5 cable is required for retrofit grants. 10BaseT
refers to the specifications for unshielded twisted pair cable (Category 3, 4, or 5)
carrying Ethernet signals. Category 6 is relatively new and is used for gigabit
connections.


Unshielded Twisted Pair Connector

The standard connector for unshielded twisted pair cabling is an RJ-45 connector.
This is a plastic connector that looks like a large telephone-style connector (See
fig. 2). A slot allows the RJ-45 to be inserted only one way. RJ stands for
Registered Jack, implying that the connector follows a standard borrowed from
the telephone industry. This standard designates which wire goes with each pin
inside the connector.




                                       [48]
                                Fig. 2. RJ-45 connector


Shielded Twisted Pair (STP) Cable
A disadvantage of UTP is that it may be susceptible to radio and electrical
frequency interference. Shielded twisted pair (STP) is suitable for environments
with electrical interference; however, the extra shielding can make the cables
quite bulky. Shielded twisted pair is often used on networks using Token Ring
topology.


Coaxial Cable
Coaxial cabling has a single copper conductor at its center. A plastic layer
provides insulation between the center conductor and a braided metal shield (See
fig. 3). The metal shield helps to block any outside interference from fluorescent
lights, motors, and other computers.




                                 Fig. 3. Coaxial cable

Although coaxial cabling is difficult to install, it is highly resistant to signal
interference. In addition, it can support greater cable lengths between network
devices than twisted pair cable. The two types of coaxial cabling are thick coaxial
and thin coaxial.

Thin coaxial cable is also referred to as thinnet. 10Base2 refers to the
specifications for thin coaxial cable carrying Ethernet signals. The 2 refers to the
approximate maximum segment length being 200 meters. In actual fact the
maximum segment length is 185 meters. Thin coaxial cable is popular in school
networks, especially linear bus networks.


                                         [49]
Thick coaxial cable is also referred to as thicknet. 10Base5 refers to the
specifications for thick coaxial cable carrying Ethernet signals. The 5 refers to the
maximum segment length being 500 meters. Thick coaxial cable has an extra
protective plastic cover that helps keep moisture away from the center conductor.




Coaxial Cable Connectors

The most common type of connector used with coaxial cables is the Bayone-
Neill-Concelman (BNC) connector (See fig. 4). Different types of adapters are
available for BNC connectors, including a T-connector, barrel connector, and
terminator. Connectors on the cable are the weakest points in any network. To
help avoid problems with your network, always use the BNC connectors that
crimp, rather than screw, onto the cable.




                              Fig. 4. BNC connector




                          Ethernet Cable Summary


          Specification          Cable Type             Maximum length

          10BaseT          Unshielded Twisted Pair      100 meters

          10Base2          Thin Coaxial                 185 meters

          10Base5          Thick Coaxial                500 meters

          10BaseF          Fiber Optic                  2000 meters

          100BaseT         Unshielded Twisted Pair      100 meters



                                         [50]
100BaseTX   Unshielded Twisted Pair   220 meters




                       [51]
[52]
                          PRACTICAL - 7
AIM: - Configure an IP address on a workstation.
How to assign/change the IP address that is assigned to a network adapter

     1.   Log on to the computer by using the Administrator account.

     2. Click Start, click Settings, and then click Control Panel.

     3. In Control Panel, double-click Network and Dial-up Connections. The Network
          and Dial-up Connections dialog box opens.

     4. Right-click the local area connection that you want, and then click Properties.
          The Local Area Network Connection Properties dialog box opens.

     5. In the Components checked are used by this connection box, click Internet
          Protocol (TCP/IP), and then click Properties. The Internet Protocol (TCP/IP)
          Properties dialog box appears.

     6. Continue with the steps in one of the following two sections.

     7. In the IP address box, type the IP address that you want to be assigned to this
          network adapter. This IP address must be a unique address in the range of
          addresses that are available for your network. Contact the network
          administrator to obtain a list of valid IP addresses for your network.

     8. In the Subnet mask box, type the subnet mask for your network

     9. In the Default gateway box, type the IP address of the computer or device on
          your network that connects your network to another network, or to the
          Internet.

     10. In the Preferred DNS server box, type the IP address of the computer that
          resolves host names to IP addresses.

     11. Click OK. In the Local Area Connection Properties dialog box, click OK.

     12. Close the Network and Dial-up Connections window
                                            [53]
                              PRACTICAL - 8


AIM: - Identify the IP address of a workstation and the class of the
address.
An IP address (Internet Protocol address) is a unique number that devices use in order to
identify and communicate with each other on a computer network utilizing the Internet Protocol
standard (IP). Any participating network device — including routers, computers, time-servers,
printers, Internet fax machines, and some telephones — must have its own unique address. An IP
address can also be thought of as the equivalent of a street address or a phone number (compare:
VoIP) for a computer or other network device on the internet. Just as each street address and
phone number uniquely identifies a building or telephone, an IP address can uniquely identify a
specific computer or other network device on a network.


An IP address can appear to be shared by multiple client devices either because they are part of a
shared hosting web server environment or because a proxy server (e.g. an ISP or anonymizer
service) acts as an intermediary agent on behalf of its customers, in which case the real
originating IP addresses might be hidden from the server receiving a request. The analogy to
telephone systems would be the use of predial numbers (proxy) and extensions (shared).
IP addresses are managed by the Internet Assigned Numbers Authority. IANA generally assigns
super-blocks to Regional Internet Registries, who in turn allocate smaller blocks to Internet
Service Providers and enterprises.


Dynamic and static IP addresses

IP addresses may either be assigned permanently (for example, to a server which is always found
at the same address) or temporarily from a pool of available addresses.


Dynamic IP addresses are issued to identify non-permanent devices such as personal computers
or clients. Internet Service Providers (ISPs) use dynamic allocation to assign addresses from a
small pool to a larger number of customers. This is used for dial-up access, WiFi and other



                                              [54]
temporary connections, allowing a portable computer user to automatically connect to a variety
of services without needing to know the addressing details of each network.




Users with a dynamic IP may have trouble running their own email server. In recent years
services such as mail-abuse.org have collected lists of these address ranges and can be used as a
block list.


The most common protocol used to dynamically assign addresses is Dynamic Host
Configuration Protocol (DHCP). DHCP includes a lease time which determines how long the
requester can use an address before requesting its renewal, allowing addresses to be reclaimed if
the requester goes offline. The DHCP server listens for requests and then assigns an address.
System administrators may set the DHCP server so that it assigns addresses at random, or based
on a predetermined policy.
Once a machine receives its new IP address, it may tell that address to a Dynamic DNS server.


Static IP addresses are used to identify semi-permanent devices with constant IP addresses.
Servers typically use static IP addresses. The static address can be configured directly on the
device or as part of a central DHCP configuration which associates the device's MAC address
with a static address.


An IP (Internet Protocol) address is a unique identifier for a node or host connection on an IP
network. An IP address is a 32 bit binary number usually represented as 4 decimal values, each
representing 8 bits, in the range 0 to 255 (known as octets) separated by decimal points. This is
known as "dotted decimal" notation.

Example: 140.179.220.200

Every IP address consists of two parts, one identifying the network and one identifying the node.
The Class of the address and the subnet mask determine which part belongs to the network
address and which part belongs to the node address.



                                              [55]
Address Classes
There are 5 different address classes. You can determine which class any IP address is in by
examining the first 4 bits of the IP address.
Class A addresses begin with 0xxx, or 1 to 126 decimal.
Class B addresses begin with 10xx, or 128 to 191 decimal.
Class C addresses begin with 110x, or 192 to 223 decimal.
Class D addresses begin with 1110, or 224 to 239 decimal.
Class E addresses begin with 1111, or 240 to 254 decimal.


Addresses beginning with 01111111, or 127 decimal, are reserved for loopback and for internal
testing on a local machine. [You can test this: you should always be able to ping 127.0.0.1,
which points to yourself] Class D addresses are reserved for multicasting. Class E addresses are
reserved for future use. They should not be used for host addresses.


Now we can see how the Class determines, by default, which part of the IP address belongs to
the network (N) and which part belongs to the node (n).


Class A -- NNNNNNNN.nnnnnnnn.nnnnnnnn.nnnnnnnn
Class B -- NNNNNNNN.NNNNNNNN.nnnnnnnn.nnnnnnnn
Class C -- NNNNNNNN.NNNNNNNN.NNNNNNNN.nnnnnnnn


In the example, 140.179.220.200 is a Class B address so by default the Network part of the
address (also known as the Network Address) is defined by the first two octets (140.179.x.x) and
the node part is defined by the last 2 octets (x.x.220.200).
In order to specify the network address for a given IP address, the node section is set to all "0"s.
In our example, 140.179.0.0 specifies the network address for 140.179.220.200. When the node
section is set to all "1"s, it specifies a broadcast that is sent to all hosts on the network.
140.179.255.255 specifies the example broadcast address. Note that this is true regardless of the
length of the node section.




                                                [56]
                                PRACTICAL – 9

To make two kinds of cables used for connecting two or
more computers


The two most common unshielded twisted-pair (UTP) network standards are the10
Mhz 10BASE-T Ethernet and the 100Mhz 100BASE-TX Fast Ethernet. The 100BASE-TX
standard is quickly becoming the predominant LAN standard. If you are starting from scratch, to
build a small home or office network, this is clearly the standard you should choose. This article
will show you how to make cables which will work with both standards.

A LAN can be as simple as two computers, each having a network interface card (NIC) or
network adapter and running network software, connected together with a crossover cable.

The next step up would be a network consisting of three or more computers and a hub. Each of
the computers is plugged into the hub with a straight-thru cable (the crossover function is
performed by the hub).




Let's start with simple pin-out diagrams of the two types of UTP Ethernet cables and watch how
committees can make a can of worms out of them. Here are the diagrams:




                                              [57]
Note that the TX (transmitter) pins are connected to corresponding RX (receiver) pins, plus to
plus and minus to minus. And that you must use a crossover cable to connect units with
identical interfaces. If you use a straight-through cable, one of the two units must, in effect,
perform the cross-over function.

Two wire color-code standards apply: EIA/TIA 568A and EIA/TIA 568B. The codes are
commonly depicted with RJ-45 jacks as follows (the view is from the front of the jacks):




If we apply the 568A color code and show all eight wires, our pin-out looks like this:




                                              [58]
Note that pins 4, 5, 7, and 8 and the blue and brown pairs are not used in either standard. Quite
contrary to what you may read elsewhere, these pins and wires are not used or required to
implement 100BASE-TX duplexing--they are just plain wasted.

However, the actual cables are not physically that simple. In the diagrams, the orange pair of
wires are not adjacent. The blue pair is upside-down. The right ends match RJ-45 jacks and the
left ends do not. If, for example, we invert the left side of the 568A "straight"-thru cable to
match a 568A jack--put one 180° twist in the entire cable from end-to-end--and twist together
and rearrange the appropriate pairs, we get the following can-of-worms:

This further emphasizes, I hope, the importance of the word "twist" in making network cables
which will work. You cannot use an flat-untwisted telephone cable for a network cable.
Furthermore, you must use a pair of twisted wires to connect a set of transmitter pins to their
corresponding receiver pins. You cannot use a wire from one pair and another wire from a
different pair.

Keeping the above principles in mind, we can simplify the diagram for a 568A straight-thru
cable by untwisting the wires, except the 180° twist in the entire cable, and bending the ends
upward. Likewise, if we exchange the green and orange pairs in the 568A diagram we will get a
simplified diagram for a 568B straight-thru cable. If we cross the green and orange pairs in the
568A diagram we will arrive at a simplified diagram for a crossover cable. All three are shown
below.




                                              [59]
[60]
[61]
                                PRACTICAL - 10

AIM: - Sharing of resources with two connected nodes

1. Mapping a network drive
Moving files between computers on a floppy disk (the so-called "sneakernet") is a thing of the
past. If you have more than one computer in your home, you can share files across your home
network. Shared folders from other computers appear in Windows Explorer just as if they were
on the computer you're using.


Sharing files is a two-step process:


1. Share a folder on the computer that stores your files.
2. Create a connection to the shared folder on the computer that you want to use to open the files.


You can connect to the shared folder in two ways:
(a) You can directly open the shared folder. This is the quickest way to get to your shared files.
                                              or
(b) You can map a drive letter to the shared folder. This way makes it easier to open the folder in
   the future.


The steps for both of these ways to connect to a shared folder on another computer on your
home network are described below.


Open a shared folder


1. On your desktop, double-click My Network Places.


Note: If My Network Places is not on your desktop, click Start, and then click My Network
Places on the Start menu.



                                                [62]
2.In My Network Places, double-click the folder you want to open.




You'll see your files in the folder.
                                             [63]
Map a drive to a shared folder



Click Start, and then click My Documents.




Click the Tools menu, and then click Map Network Drive.




                                            [64]
In the Map Network Drive dialog box, click Browse.




                                          [65]
In the Browse For Folder dialog box, click the folder you want to connect to, and then click
OK.




In the Map Network Drive dialog box, make a note of the drive letter shown, and then click
Finish.




                                              [66]
If prompted, type your user name and password, and then click OK.




                                            [67]
                                 PRACTICAL - 11
Use of net stat and its switches

netstat (=network statistics) is a command-line tool that displays a list of the active network
connections the computer currently has, both incoming and outgoing. It is available on Unix,
Unix-like, and Windows NT-based operating systems.


On the Windows platform, netstat information can be retrieved by calling the GetTcpTable and
GetUdpTable functions in the IP Helper API, or IPHLPAPI.DLL. Information returned includes
local and remote IP addresses, local and remote ports, and (for GetTcpTable) TCP status codes.
In addition to the command-line netstat.exe tool that ships with Windows, there are GUI-based
netstat programs available


Syntax
netstat [-a] [-e] [-n] [-o] [-p Protocol] [-r] [-s] [Interval]



                                                   [68]
Windows: netstat /?


Parameters
-a : Displays all active TCP connections and the TCP and UDP ports on which the computer is
listening.
-b : Displays the binary (executable) program's name involved in creating each connection or
listening port.
-e : Displays extended statistics, such as the number of bytes and packets sent and received. This
parameter can be combined with -s.
-n : Displays active TCP connections, however, addresses and port numbers are expressed
numerically and no attempt is made to determine names.
-o : Displays active TCP connections and includes the process ID (PID) for each connection.
You can find the application based on the PID on the Processes tab in Windows Task Manager.
This parameter can be combined with -a, -n, and -p. This parameter is available on Microsoft
Windows XP, 2003 Server (not Microsoft Windows 2000)).


-p Protocol : Shows connections for the protocol specified by Protocol. In this case, the Protocol
can be tcp, udp, tcpv6, or udpv6. If this parameter is used with -s to display statistics by
protocol, Protocol can be tcp, udp, icmp, ip, tcpv6, udpv6, icmpv6, or ipv6.


-r : Displays the contents of the [[IP routing table]]. This is equivalent to the route print
command.
-s : Displays statistics by protocol. By default, statistics are shown for the TCP, UDP, ICMP, and
IP protocols. If the IPv6 protocol for Windows XP is installed, statistics are shown for the TCP
over IPv6, UDP over IPv6, ICMPv6, and IPv6 protocols. The -p parameter can be used to
specify a set of protocols.
-v : When used in conjunction with -b it will display the sequence of components involved in
creating the connection or listening port for all executables.


Interval : Redisplays the selected information every Interval seconds. Press CTRL+C to stop the
redisplay. If this parameter is omitted, netstat prints the selected information only once.


/? : Displays help at the command prompt.
                                                [69]
[70]

				
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