8/2/2019 Basic Networking Knowledge
1/183
8/2/2019 Basic Networking Knowledge
2/183
2
TOPICS
# I NTRODUCTI ON# COMPUTI NG MODELS# NETWORK CLASSI FI CATI ON# NETWORK SERVI CES# TRANSMI SSI ON MEDI A# PHYSI CAL LAYER# NETWORK TOPOLOGI ES# NETWORKI NG PROTOCOLS# NETWORKI NG HARDWARE
8/2/2019 Basic Networking Knowledge
3/183
3
8/2/2019 Basic Networking Knowledge
4/183
4
Define Computer Networking
Networking is the sharing ofinformation and services. Computer
networking provides thecommunication tools to allowcomputers to share information and
abilities.
Network
By a computer network we mean an interconnected set of
autonomous computers. By autonomous we mean each of them can
function independent of the others.
8/2/2019 Basic Networking Knowledge
5/183
5
A network consists of two or more computersthat are linked in order to share resources
(such as printers and CD-ROMs), exchange
files, or allow electronic communications.The computers on a network may be linked
through cables, telephone lines, radiowaves, satellites, or infrared light beams.
Network
8/2/2019 Basic Networking Knowledge
6/183
6
8/2/2019 Basic Networking Knowledge
7/183
7
Computer networking are based on the following
computing models :-
Distributed computing
Collaborative computing
Computing Models and Network
Development
8/2/2019 Basic Networking Knowledge
8/183
8
The following computing models are usedto categorize the way networking servicesare provided:
Client/Server
Client/Network
Computing models
8/2/2019 Basic Networking Knowledge
9/183
9
In the centralized computing model, largecentralized computers, called mainframes, areused to store and organize data. People enter
data on mainframes using local devicescalled terminals.
In centralized computing, the mainframeprovides all the data storage andcomputational abilities; the terminal is simplya remote input/output device.
Centralized Computing
8/2/2019 Basic Networking Knowledge
10/183
8/2/2019 Basic Networking Knowledge
11/183
11
Collaborative computing (also called
cooperative processing) is a type of
distributed computing using networked
computers that collaborate by sharing
processing abilities .
Collaborative Computing
8/2/2019 Basic Networking Knowledge
12/183
12
Collaborative computing allows computers to
request processing resources from othercomputers as needed.
Collaborative computing is a form ofdistributed computing.
Collaborative computing allows tasks to be
shared by computers as needed.
Distributed computing assigns each task to asingle computer.
Both use networked computers withprocessing capabilities; and both divide
applications into tasks.
8/2/2019 Basic Networking Knowledge
13/183
13
In the client/server computing model, several clients
(PCs) are connected to a server (PC)...
In the client/server model :-
Processing capabilities are distributed across multiple,machines .
Clients request services from servers.
The server performs some of the processing for theclient.
Applications used in a client/server network can besplit into a front end that runs on the client and a backend that runs on the server.
Client/Server Computing
8/2/2019 Basic Networking Knowledge
14/183
14
Standalone (non-networked) applications such as a
spreadsheet program or a word processing programthat runs on the client but saves its data on the server.
A database application that provides a clientinterface for requests and a search engine on the
server that locates records stored on one or moreservers
Programs, such as an email system, that use the
server to share information
In Client/server model, the following can be us
8/2/2019 Basic Networking Knowledge
15/183
15
8/2/2019 Basic Networking Knowledge
16/183
16
Local Area Network (LAN)
Metropolitan Area Networks
(Man) Wide Area Networks (WAN)
Computer Network Classifications
8/2/2019 Basic Networking Knowledge
17/183
17
These are privately-owned communication
systems that cover a short distance i,.E ABUILDING OR A CAMPUS OF BUILDINGS.
Variety of devices including computers,
terminals, peripheral devices and sensors are
used to link using a LAN. LANs OPERATE AT
A HIGH SPEED (i.E 10 mbps OR MORE ANDHAVE A VERY LOW ERROR RATE (1:1011).
LANs
8/2/2019 Basic Networking Knowledge
18/183
18
Local Area Network (LAN)
A LAN is normally contained within abuilding or campus and typically usescommunication links that are owned
and maintained by the group whosedata the LAN carries .
LAN transmission speeds are oftenmeasured in megabits per second(mbps ).
8/2/2019 Basic Networking Knowledge
19/183
19
These can be considered as a bigger version of a
LAN, typically covering a city. It can be eitherpublic or privately owned. Although LAN
technology can be used in man, it has been
distinguished as a separate type of network,
because of the specific standard known as
distributed queue double bus (DQDB) that hasbeen adopted for man. The DQDB comprises of
two unidirectional buses for connecting
computers
MAN
8/2/2019 Basic Networking Knowledge
20/183
20
Wan encompasses a large geographical area, often acountry or a sub-continent, or the entire globe.
Communication is usually done through public
communication systems such as telephone network.
As a consequence, data transfer rate in WAN is low
(several kb/s). Error rate is much higher (1000 times
that of lan), which requires use of suitable error
handling technique.
Wan
8/2/2019 Basic Networking Knowledge
21/183
21
A wide area network (WAN) comprises multipleLANs.
WANs interconnect LANs that can be atopposite sides of a country or located around the
world. WANs often use telephone or satellitecommunication .
Access to WAN links is often leased from a
WAN services vendor who is responsible formaintaining the communication equipment.
For most WAN links, the transmission speedattainable over the available bandwidth ismeasured in kilobits er second kb s .
Wide Area Networks (WAN)
8/2/2019 Basic Networking Knowledge
22/183
8/2/2019 Basic Networking Knowledge
23/183
23
Enterprise and Global Networks
A global network is to cover the entire globe, but
they cross multiple nations that span the earth.
Global networks might not boundaries and caninclude the networks of several organizations
The Internet is a good example of a globalnetwork
8/2/2019 Basic Networking Knowledge
24/183
24
Enterprise and Global
Networks
8/2/2019 Basic Networking Knowledge
25/183
25
INTERNET IS NOT A SEPARATE KIND OF NETWORK,
BUT IT IS A COLLECTION OF NETWORKS OR AANETWORK OF NETWORKSNETWORK OF NETWORKS. ONE PRIMARY GOAL OF
INTERNET IS TO CONNECT VARIOUS NETWORKS IN
A SEAMLESS MANNER. THE GLUE WHICH HOLD
VARIOUS NETWORKS TOGETHER IS THE TCP-IP,
THAT ALLOWS HOSTS TO COMMUNICATE FREELY
ACROSS NETWORK BOUNDARIES. INTERNET
ALLOWS VARIOUS APPLICATIONS SUCH AS E-MAIL,FILE TRANSFER, REMOTE LOGIN AS IN NEWS,
WORLD WIDE WEB, MULTIMEDIA, ETC.
INTERNET
8/2/2019 Basic Networking Knowledge
26/183
26
ADVANTAGES
Speed. Networks provide a very rapid method for sharing and
transferring files.
Lower Cost. A network of low-cost computers gives much better
cost/performance than a single costly mainframe computer..Besides monetary savings, sharing a program on a network
allows for easier upgrading of the program
Security. Files and programs on a network can be designated as
"copy inhibit," Also, passwords can be established for specific
directories to restrict access to authorized users
NEED OF COMPUTER NETWORKING
Centralized Software Management All of the software can be
8/2/2019 Basic Networking Knowledge
27/183
27
Centralized Software Management. All of the software can be
loaded on one computer (the file server). This eliminates
that need to spend time and energy installing updates and
tracking files on independent computers throughout the
building
Communication medium: It offers a powerful communicating
medium among a group of people widely separated.
Resource sharing: Most organisations cannot afford enough
laser printers, fax machines, modems, scanners, and CD-
ROM players for each computer. However, resources likedata, program, costly peripherals or equipments located at
distant places can be shared through network.
El t i M il Th f t k id th
8/2/2019 Basic Networking Knowledge
28/183
28
Electronic Mail. The presence of a network provides the
hardware necessary to install an e-mail system. Electronic
mail on a LAN can enable users to communicate with each
other. If the LAN is connected to the Internet, users can
communicate with others throughout the world
Higher reliablility: A computer network offers higher
reliability than a centralised computing environment
because of the redundancy that can be incorporated both interms of hardware and software. in the event of failure of
one computer, its work-load can be taken over by other
computer.
Higher flexibility: Computer networks allow communication
among heterogeneous systems, which give users betterflexibility
DISADVANTAGES
8/2/2019 Basic Networking Knowledge
29/183
29
Expensive to Install. Although a network will generally
save money over time, the initial costs of installation can
be prohibitive. Cables, network cards, and software are
expensive, and the installation may require the services of
a technician.
Requires Administrative Time. Proper maintenance of anetwork requires considerable time and expertise.
File Server May Fail. Although a file server is no more
susceptible to failure than any other computer, when the
files server "goes down," the entire network may come to
a halt.
DISADVANTAGES
8/2/2019 Basic Networking Knowledge
30/183
30
Cables May Break. Some of the configurations aredesigned to minimize the inconvenience of a broken
cable; with other configurations, one broken cable can
stop the entire network.
No Privacy As programs and data are shared by many
users, this raises the problem of data integrity, securityand privacy.
No ControlIn a distributed system there is certain
amount of loss of control. It is difficult to enforce
standards for software and data.
8/2/2019 Basic Networking Knowledge
31/183
31
Network Services
8/2/2019 Basic Networking Knowledge
32/183
32
Network services are the capabilities that
networked computers share.
Network services are provided by numerouscombinations of computer hardware and
software. Depending upon the task, networkservices require data, input/output resources,
and processing power to accomplish their
Network Services
8/2/2019 Basic Networking Knowledge
33/183
33
ServersServers are classified as service providers.They only provide services.
ClientsClients are classified as service requesters.They only request services.
PeersPeers can be classified as both a servicerequester or provider. They provide and
request services.
The three types of service providers andrequesters:
Network Operating Systems
8/2/2019 Basic Networking Knowledge
34/183
34
Computer networks are often classifiedas one of the following types:
Peer-to-peer Server-centric
Network Operating Systems
Network operating systems (NOS) coordinate theactivities of multiple computers across a network. The
network operating system acts as a director to keepthe network running smoothly. The two major types ofnetwork operating systems are:
8/2/2019 Basic Networking Knowledge
35/183
35
Peer-to-peer networksallow any entity to both
request and provide networkservices.
Peer-to-peer networksoftware is designed so that
peers perform the same orsimilar functions for each
Peer-to-Peer Networks
8/2/2019 Basic Networking Knowledge
36/183
36
Advantages & Disadvantages
Less initial expense - No
need for a dedicated server.
Set-up - An operating
system (such as Windows95) already in place may
only need to be
reconfigured for peer-to-peer operations.
Decentralized - No
central control for filesand applications.
Security - Does notprovide the security
available on a
client/server network.
S C t i N t k
8/2/2019 Basic Networking Knowledge
37/183
37
@ Client/server network operating systems allow the network
to centralize functions and applications in one or more
dedicated file servers. The File servers provide access toresources and providing security.
@ Individual workstations (clients) have access to the
resources available on the file servers
@ The network operating system provides the mechanism to
integrate all the components of the network and allow multiple
users to simultaneously share the same resources irrespective
of physical location.
@ Novell Netware and Windows NT Server are examples of
client/server network operating systems.
Server-Centric Networks
Ad & Di d
8/2/2019 Basic Networking Knowledge
38/183
38
Centralized - Resources and datasecurity are controlled through the
server.Scalability - Any or all elementscan be replaced individually asneeds increase.
Flexibility - New technology can beeasily integrated into system.
Interoperability - All components(client/network/server) work
together.Accessibility - Server can beaccessed remotely and acrossmultiple platforms.
Expense - Requiresinitial investment in
dedicated server.
Maintenance - Largenetworks will require
staff to ensure efficientoperation.
Dependence - Whenserver goes down,operations will ceaseacross the network.
Advantages & Disadvantages
Online Nearline and
8/2/2019 Basic Networking Knowledge
39/183
39
Online, Nearline, and
Offline Storage Media
Computers store data on a variety ofComputers store data on a variety of
8/2/2019 Basic Networking Knowledge
40/183
40
Computers store data on a variety ofComputers store data on a variety of
magneticmagnetic
and optic disks, diskettes, and tapes.and optic disks, diskettes, and tapes.
Online storage media, such as hard disks,
areimmediately available to the computer.
Nearline storage media, such as tapecarousels,
CD jukeboxes, and so on, are not
immediatelyavailable to the computer, but do not require
human intervention .
Offline storage media, such as removable
8/2/2019 Basic Networking Knowledge
41/183
File Update Synchronization
8/2/2019 Basic Networking Knowledge
42/183
42
File Update Synchronization
8/2/2019 Basic Networking Knowledge
43/183
43
Typically, only two or threecomputers can be directly connected
to each printer.
On the other hand, network
print services allow numerous clients
to be serviced
by a single printer.
Network Printing
Advantages of network printing
8/2/2019 Basic Networking Knowledge
44/183
44
Reducing the total number of printers cansave your organization a substantial amount of
money. Having fewer printers reduces thenumber of devices to buy, maintain, and
manage.
Advantages of network printing
8/2/2019 Basic Networking Knowledge
45/183
45
Network Printing
Network Message Services
8/2/2019 Basic Networking Knowledge
46/183
46
Message services include storing,
accessing,and delivering text, binary, graphic,digitized
video, and audio data.
Message services deal withcommunication
between computer users, user
applications,
Network Message Services
Network message services help
8/2/2019 Basic Networking Knowledge
47/183
47
Network message services help
you Exchange computer-generated notes
and files Integrate electronic mail with voice
mail systems Route and share data using workflow
and linked object documentapplications
Organize and maintain user anddevice information directories
8/2/2019 Basic Networking Knowledge
48/183
48
In this subsection types of message-
enabled
applications:
Electronic mail
Integrated electronic mail and voicemail
Workgroup applications
Network Message Services
8/2/2019 Basic Networking Knowledge
49/183
49
Network Message Services
D b R li i
8/2/2019 Basic Networking Knowledge
50/183
50
Data can be retrieved much more rapidly
from local databases than from remote
databases .Therefore, it is often more
efficient for users to work on a local copy
of the data .
Replication creates and synchronizes
multiple copies of a database over the
Database Replication
Distributed Database Replication
8/2/2019 Basic Networking Knowledge
51/183
51
Distributed Database Replication
Methods
8/2/2019 Basic Networking Knowledge
52/183
52
DATA COMMUNICATION CONCEPTS
8/2/2019 Basic Networking Knowledge
53/183
53
The primary concern of a computer network is to facilitate
exchange of information between any pair of nodes in thenetwork. That involves sending of data in the form of signal
from source node to the destination node through A
communication channel. The key issues are:The nature of data
Physical means used to transfer data
Processing of data for efficient communication.
CO UN C ON CONC S
BLOCK DIAGRAM OF TYPICAL COMMUNICATION SYSTEM
8/2/2019 Basic Networking Knowledge
54/183
54
SOURCE
NODE
DESTINATION
NODE
SIGNAL INPUT
TRANSMITTER
TRANSMISSION
CHANNEL
RECEIVER
SIGNAL OUTPUT
COMMUNICATION SYSTEM
8/2/2019 Basic Networking Knowledge
55/183
55
TRANSMISSION MEDIA
In a network of computers, the transmission
media provide the physical path for communicationamong the nodes and the manner in which the nodes
are geometrically interconnected is known as its
topology.
Examples for guided transmission media are twisted-
pair of wires, co-axial cables and optical fiber
Pathway for Communication
8/2/2019 Basic Networking Knowledge
56/183
56
Pathway for Communication
Transmission Media
8/2/2019 Basic Networking Knowledge
57/183
57
Computer transmission media includescable
and wireless technologies that allownetworked
devices to contact one another.
Transmission media cannot guarantee that
other network devices will understand a
message.
It can, however, guarantee a message
C bl M di
8/2/2019 Basic Networking Knowledge
58/183
58
Cable media are wires or fibers that conductelectricity or light.
The following examples are covered in this section:
Twisted pair cable
Coaxial cable
Fiber optic cable
Cable Media
Twisted pair cable
8/2/2019 Basic Networking Knowledge
59/183
59
Twisted pair (TP) cable uses copper wire astelecommunication cable.
Because copper is such a good conductor of electrons,copper wires do not constrain electromagnetic signals
well. Twisted pair can be used for both Analog and Digitalcommunication
Twisting the copper wires reduces cross talk and signalemissions.
Each intertwined strand conducts a current whoseemitted waves are cancelled out by the other wires
Twisted Pair
8/2/2019 Basic Networking Knowledge
60/183
60
Twisted Pair
8/2/2019 Basic Networking Knowledge
61/183
61
TWISTED-PAIRCharacteristics:-Twisted pair can be used for both analog
and digital communication. The data rate that can be
supported over a twisted pair is inversely proportional tothe square of the line length. Maximum transmission
distance of 1km can be achieved for data rates up to
1mb/s. For digital signal, repeaters are needed for about2km. To reduce interference, the twisted pair can be
shielded with metallic braid. This type of wire is known as
shielded twisted pair(STP) and the other is known asunshielded twisted pair(UTP).
The Electrical Industries Association (EIA)popularized a category labeling scheme for five
8/2/2019 Basic Networking Knowledge
62/183
62
popularized a category labeling scheme for five
different qualities of twisted pair cable:
Category 1 and 2: Voice and low-speed data (lessthan or equal to 4 Mbps)
Category 3: Data (typically 10-16 Mbps, although100 Mbps is possible)
Category 4: Data (less than or equal to 20 Mbps)Category 5: High-speed data (less than or equal to100 Mbps)
Category 3 and Category 5 UTP are commonly usedin computer networking. Category 3 is suitable formost computer networks.
8/2/2019 Basic Networking Knowledge
63/183
63
The two types of TP cable are :
Unshielded
Shielded
Unshielded Twisted Pair Cable
8/2/2019 Basic Networking Knowledge
64/183
64
Unshielded Twisted Pair Cable
8/2/2019 Basic Networking Knowledge
65/183
65
UTP is commonly used in telephone systems. It
is widely available and has been largely standardized.
The standard connector for
unshielded twisted pair
cabling is an RJ-45
connector. This is a plasticconnector that looks like a
large telephone-style
connector
A Common Unshielded Twisted PairInstallation
8/2/2019 Basic Networking Knowledge
66/183
66
Installation
Shielded Twisted Pair Cable
8/2/2019 Basic Networking Knowledge
67/183
67
Shielded Twisted Pair Cable
A disadvantage of UTP is that it may be
susceptible to radio and electrical frequencyinterference. 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 usingToken Ring topology.
Shielded Twisted Pair Cable
8/2/2019 Basic Networking Knowledge
68/183
68
Today, most TP cable is unshielded, but some
forms of shielded twisted pair(STP) still exist.
STP is insulated cable that includes bundledpairs wrapped in a foil shielding. Various
transmission media specifications from Apple
Computer and IBM use STP cable.
Shielded Twisted Pair
8/2/2019 Basic Networking Knowledge
69/183
69
Shielded Twisted Pair Installation
8/2/2019 Basic Networking Knowledge
70/183
70
Coaxial Cable
8/2/2019 Basic Networking Knowledge
71/183
71
Coaxial cable (commonly called coax) is made of twoconductors that share a common axis, hence the name
(co, axis).
Typically, the center of the cable is a relatively stiffsolid copper wire or stranded wire encased in
insulating plastic foam.
The foam is surrounded by the second conductor, awire mesh tube (some include conductive foil wrap),which serves as a shield from interference and signalcapture.
A tough, insulating plastic tube forms the cover of thecable.
Coaxial Cable
8/2/2019 Basic Networking Knowledge
72/183
72
Coaxial cable standards are
used in computer networking
8/2/2019 Basic Networking Knowledge
73/183
73
The most common types meet one of the following ohmand size standards (ohms are a measurement of the
cables resistance to direct or alternating electriccurrents):
75 ohm RG-6 (used for Satellite TV)
50 ohm RG-8 and RG-11 (used in thick Ethernetspecifications discussed later)
50 ohm RG-58 (used in thin Ethernet specificationsdescribed later)
75 ohm RG-59 (used for cable TV and cable modems)
93 ohm RG-62 (used for ARC net specifications)
Common Coaxial Cable Installation
8/2/2019 Basic Networking Knowledge
74/183
74
Fiber Optic Cable
8/2/2019 Basic Networking Knowledge
75/183
75
Fiber optic cables can be composed of a singlejacketed strand, but often multiple strands are bundled
in the center of a cable. Some fiber optic cables alsoprovide an additional metallic, or fiberglass wire toincrease cable strength.
Optical fibers can be multimode or single mode innature. Single-mode fiber has been optimized to allowonly one light path; multimode fiber allows various
light paths.
Single-mode fiber has a higher capacity but costsmore to produce and use than multimode fiber.
Fiber Optic Cable
8/2/2019 Basic Networking Knowledge
76/183
76
Type of Fiber-Optic Cable
8/2/2019 Basic Networking Knowledge
77/183
77
Single-Mode and
Multimedia Propagation
8/2/2019 Basic Networking Knowledge
78/183
78
8/2/2019 Basic Networking Knowledge
79/183
Cable Transmission MediaComparison
8/2/2019 Basic Networking Knowledge
80/183
80
p
8/2/2019 Basic Networking Knowledge
81/183
81
RADIO WAVERADIO WAVE
MICROWAVEMICROWAVE
INFRARED LIGHTINFRARED LIGHT
Radio Wave
8/2/2019 Basic Networking Knowledge
82/183
82
The portion of the electromagnetic spectrum that isusually considered radio frequency (RF) resides
between 10 KHz and 1 GHz. This range of radiofrequencies includes broadcast bands for :
Shortwave radio
Very high frequency (VHF) television and FM radio
Ultra-high frequency (UHF) radio and television
Radio frequencies are divided between regulatedand unregulated bandwidths.
Radio Frequencies
8/2/2019 Basic Networking Knowledge
83/183
83
8/2/2019 Basic Networking Knowledge
84/183
8/2/2019 Basic Networking Knowledge
85/183
85
Wireless LANs have gained strongWireless LANs have gained strong
popularity in a number of verticalpopularity in a number of vertical
8/2/2019 Basic Networking Knowledge
86/183
86
the health-care retail
manufacturing
warehousing
academic
markets including :markets including :
Wi h i l LAN h d
Why wireless?
8/2/2019 Basic Networking Knowledge
87/183
87
With wireless LANs, users can access sharedinformation without looking for a place to plug in,and network managers can set up or augmentnetworks without installing or moving wires.
Wireless LANs Technology
8/2/2019 Basic Networking Knowledge
88/183
88
Manufacturers of wireless LANs have arange of technologies to choose from when
designing a wireless LAN solution.
Each technology comes with its own set of
advantages and limitations.
Narrowband Technology
8/2/2019 Basic Networking Knowledge
89/183
89
A narrowband radio system transmits and receives
user information on a specific radio frequency. Narrowband radio keeps the radio signal frequencyas narrow as possible just to pass the information.
Broad Band/Spread Spectrum Technol
8/2/2019 Basic Networking Knowledge
90/183
90
Most wireless LAN systems use spreadspectrum technology, a wideband radiofrequency technique developed by the
military for use in reliable, secure, mission-critical communications systems.
Spread-spectrum is designed to trade offbandwidth efficiency for reliability, integrity,and security.
If a receiver is not turned to the right
freq enc a spread spectr m signal looks
8/2/2019 Basic Networking Knowledge
91/183
91
frequency, a spread-spectrum signal lookslike background noise.
There are two types of spread spectrum
radio:
Frequency hoppingand Direct sequence.
Direct Sequence Spread
Spectrum
8/2/2019 Basic Networking Knowledge
92/183
92
Multiple subsets can be used within any frequencyrange, direct sequence signals can coexist with other
signals.
Unwanted signals are simply ignored or treated as aspurious signal or noise.
Direct sequence signals can be intercepted almostas easily as other RF signals, eavesdropping isineffective because it is quite difficult to determinewhich specific frequencies to monitor, retrieve all thechips, identify valid data, and interpret the signal.
Spectrum
Direct Sequence SpreadSpectrum
8/2/2019 Basic Networking Knowledge
93/183
93
Frequency Hopping Spread
Spectrum
8/2/2019 Basic Networking Knowledge
94/183
94
Frequency hopping quicklyswitches between pre-
determined frequencies.Both transmitter andreceiver must follow the
same pattern and maintaincomplex timing intervals.
Spectrum
FHSS appears to be short-duration impulse noise.
Microwave
8/2/2019 Basic Networking Knowledge
95/183
95
Microwave data communication systems exist in two
forms:
Terrestrial (earth-based) systems
Satellite systems
8/2/2019 Basic Networking Knowledge
96/183
Terrestrial microwave
8/2/2019 Basic Networking Knowledge
97/183
97
Terrestrial microwave typically uses directional
parabolic antennas that require an unobstructed
path or line of sight to other units. Terrestrial
microwave signals, commonly in the low GHz
frequency range, are generated by a transceiver.
They are often used to link separate buildings
where cable installation would be Troublesome ormore expensive.
Satellite microwave
8/2/2019 Basic Networking Knowledge
98/183
98
Satellite microwave typically uses low GHz
frequency range microwaves.
They use parabolic antennas located on
earth and orbiting satellites
Infrared Technology
8/2/2019 Basic Networking Knowledge
99/183
99
Infrared (IR) : Systems use very high
frequencies, (100 Ghz-1000Terahertz) just belowvisible light in the electromagnetic spectrum, tocarry data.
Like light, IR cannot penetrate opaque objects,it is either directed (line-of-sight) or diffusetechnology.
Inexpensive directed systems provide verylimited range (3 ft) and typically are used forpersonal area networks but occasionally areused in specific wireless LAN applications.
Infrared links use LEDs, Laser Diodes,Photodiodes to exchange data between stations
8/2/2019 Basic Networking Knowledge
100/183
100
Transmission Media Connectors
T i i di t tt h
8/2/2019 Basic Networking Knowledge
101/183
101
Transmission media connectors attachdirectly to the transmission media and
serve as the physical interface between themedia and computing devices. Everymedium has one or more physical
connectors that you can use.
8/2/2019 Basic Networking Knowledge
102/183
Transmission Media ConnectorInstallation
8/2/2019 Basic Networking Knowledge
103/183
103
8/2/2019 Basic Networking Knowledge
104/183
104
8/2/2019 Basic Networking Knowledge
105/183
105
In 1977, the International Organization for
standardization (ISO) created the Open SystemsInterconnection (OSI) Reference Model.
OSI defines standards by which computerscan communicate together
It describes the architecture, protocols and
services required to achieve this goalThe reference model serves seven OSI layersthey are as follows:-
OSI reference modelOSI reference model
8/2/2019 Basic Networking Knowledge
106/183
106
The OSI reference modelThe OSI reference model
8/2/2019 Basic Networking Knowledge
107/183
107
Headers and the OSI ReferenceHeaders and the OSI Reference
ModeMode
8/2/2019 Basic Networking Knowledge
108/183
108
Each layer adds its own control
information, called a header, whichcontains that layers requests orinformation. This header is read and
processed by the peer layer.
Headers and the OSI Reference ModelHeaders and the OSI Reference Model
8/2/2019 Basic Networking Knowledge
109/183
109
OSI Reference Model as a ConceptualOSI Reference Model as a Conceptual
FrameworkFramework
8/2/2019 Basic Networking Knowledge
110/183
110
8/2/2019 Basic Networking Knowledge
111/183
Connection Type MethodsConnection Type Methods
8/2/2019 Basic Networking Knowledge
112/183
112
Point-to-point
Multipoint
Connection Type MethodsConnection Type Methods
8/2/2019 Basic Networking Knowledge
113/183
113
Point-to-Point Connections
8/2/2019 Basic Networking Knowledge
114/183
114
A point-to-point connection is a direct link
between two devices. When you attach a personal
computer directly to a printer, you have created a
point-to-point link. Another example is the linkbetween two microwave antennas.
A direct connection between a computer and a
printer is a common example of a point-to-point
connection.
PointPoint--toto--Point ConnectionsPoint Connections
8/2/2019 Basic Networking Knowledge
115/183
115
8/2/2019 Basic Networking Knowledge
116/183
Multipoint ConnectionsMultipoint Connections
8/2/2019 Basic Networking Knowledge
117/183
117
8/2/2019 Basic Networking Knowledge
118/183
118
Network Topologies
In a network of computers the manner in which
8/2/2019 Basic Networking Knowledge
119/183
119
There are two types of topology: physical and logical.
The physical topology of a network refers to theconfiguration or the actual layout of cables,
computers, and other peripherals. Logical topology is
the method used to pass the information betweenworkstations.
In a network of computers, the manner in which
multiple nodes are physically interconnected is referred
to as its topology.
Physical Topology Methods
8/2/2019 Basic Networking Knowledge
120/183
120
Common Physical Topologies
8/2/2019 Basic Networking Knowledge
121/183
121
Physical Topologies
8/2/2019 Basic Networking Knowledge
122/183
122
Linear Bus
Ring
Star
Mesh
Cellular
Linear Bus
A linear bus topology consists of a main long cable called a
8/2/2019 Basic Networking Knowledge
123/183
123
backbone to which network devices are either directly attached
or are attached using short drop cables .
Ethernet and Local Talk networks can use a linear bus topology.
Advantages & Disadvantages
Easy to connect a Entire network shuts down if
8/2/2019 Basic Networking Knowledge
124/183
124
computer or
peripheral to a
linear bus.
Requires less cable
length than a star
topology.
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.
Typical Bus Topology LAN
8/2/2019 Basic Networking Knowledge
125/183
125
A physical ring is
Ring
8/2/2019 Basic Networking Knowledge
126/183
126
A physical ring is
a circulartopology. Eachdevice connects
directly to the ringor indirectly
through aninterface deviceand drop cable.
Typical Physical Ring TopologyLAN
8/2/2019 Basic Networking Knowledge
127/183
127
Star
A l
8/2/2019 Basic Networking Knowledge
128/183
128
A star topology uses acentral device with dropcables extending in all
directions. Eachnetworked device is
connected via a point-to-point link to a hub.
Physical Star Topology
8/2/2019 Basic Networking Knowledge
129/183
129
Star
8/2/2019 Basic Networking Knowledge
130/183
130
Advantages & Disadvantages
Easy to install and wire.
N di ti t th
Requires more cable
length than a linear
8/2/2019 Basic Networking Knowledge
131/183
131
No disruptions to the
network whenconnecting or removing
devices.
Easy to detect faults andto remove parts.
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.
Star-Wired Ring
i d i l
8/2/2019 Basic Networking Knowledge
132/183
132
A star-wired ring topology may appear
(externally) to be the same as a startopology. Internally, the MAU (multi-
station access unit) of a star-wired ringcontains wiring that allows information to
pass from one device to another in a circle
or ring. The Token Ring protocol uses a
star-wired ring topology.
Star-Wired Ring
8/2/2019 Basic Networking Knowledge
133/183
133
Tree
A l bi h i i f
8/2/2019 Basic Networking Knowledge
134/183
134
A tree topology combines characteristics of
linear bus and star topologies. It consists ofgroups of star-configured workstations
connected to a linear bus backbone cableTree topologies allow for the expansion of
an existing network, and enable schools to
configure a network to meet their needs.
Tree
8/2/2019 Basic Networking Knowledge
135/183
135
Advantages & Disadvantages
Point to point O erall length of each
8/2/2019 Basic Networking Knowledge
136/183
136
Point-to-point
wiring forindividual
segments.
Supported by
several hardware
and software
vendors.
Overall length of each
segment is limited by the typeof cabling used.
If the backbone line breaks,
the entire segment goes
down.
More difficult to configureand wire than other
topologies.
A mesh network has point-to-pointi b d i i h
Mesh Topology
8/2/2019 Basic Networking Knowledge
137/183
137
connections between every device in the
network.
Each device requires an interface for every
other device on the network, a true meshtopology is not usually considered practical.
Unless each workstation frequently sendssignals to all other workstations, an excessiveamount of network bandwidth is wasted.
Physical Mesh Topology
8/2/2019 Basic Networking Knowledge
138/183
138
Typical Physical Mesh TopologyLAN
8/2/2019 Basic Networking Knowledge
139/183
139
A cellular topology combines wireless point-to-
Cellular topology
8/2/2019 Basic Networking Knowledge
140/183
140
point and multipoint strategies to divide a
geographic area into cells. Each cell represents the
portion of the total network area in which a specific
connection operates.
Cellular topologies exhibit qualities that are very
different from cable topologies. For example,
devices can roam from cell to cell while maintaininga connection to the network.
Physical Cellular Topology
8/2/2019 Basic Networking Knowledge
141/183
141
As a wireless structure, the topology does not
Physical Cellular TopologyLAN
8/2/2019 Basic Networking Knowledge
142/183
142
depend on the interconnection of cable.
Cellular topology relies on the location of
wireless media hubs.
Devices within the cell communicate with a
central station or hub. Hubs are interconnected
so that they route data across the network and
provide the complete network infrastructure.
Typical Physical Cellular TopologyLAN
8/2/2019 Basic Networking Knowledge
143/183
143
Considerations for Choosing aTopology
Money. A linear bus network may be the least
8/2/2019 Basic Networking Knowledge
144/183
144
y yexpensive way to install a network; you do nothave to purchase concentrators.
Length of cable needed. The linear bus networkuses shorter lengths of cable.
Future growth. With a star topology, expanding anetwork is easily done by adding anotherconcentrator.
Cable type. The most common cable in LAN isunshielded twisted pair (Cat. 5), which is mostoften used with star topologies.
8/2/2019 Basic Networking Knowledge
145/183
145
Networking Protocols
The most common protocols are:
8/2/2019 Basic Networking Knowledge
146/183
146
The most common protocols are:
Ethernet
Local Talk
Token Ring FDDI
Ethernet
The Ethernet protocol is by far the most widely used.
Ethernet uses an access method called CSMA/CD (Carrier Sensei A /C i i i )
8/2/2019 Basic Networking Knowledge
147/183
147
Multiple Access/Collision Detection).
This is a system where each computer listens to the cable beforesending anything through the network.
Sometimes, two computers attempt to transmit at the same instant.When this happens a collision occurs. Each computer then backs
off and waits a random amount of time before attempting toretransmit.
With this access method, it is normal to have collisions.
However, the delay caused by collisions and does not normallyeffect the speed of transmission on the network. The Ethernet
protocol allows for linear bus, star, or tree topologies. Data can betransmitted over twisted pair, coaxial, or fiber optic cable at aspeed of 100 Mbps.
Ethernet Cards
8/2/2019 Basic Networking Knowledge
148/183
148
Local Talk
Local Talk is a network protocol that was developed by AppleComputer, Inc. for Macintosh computers. The method used by iscalled CSMA/CA (Carrier Sense Multiple Access with Collision
8/2/2019 Basic Networking Knowledge
149/183
149
called CSMA/CA (Carrier Sense Multiple Access with Collision
Avoidance).It is similar to CSMA/CD except that a computer signals its intentto transmit before it actually does so.
The Macintosh operating system allows the establishment of apeer-to-peer network without the need for additional software.
With the addition of the server version of AppleShare software, aclient/server network can be established.
The Local Talk protocol allows for linear bus, star, or treetopologies using twisted pair cable. A primary disadvantage of
Local Talk is speed. Its speed of transmission is only 230 Kbps.
Token Ring
The Token Ring protocol was developed by IBM in the mid-1980s.
The access method used involves token-passing. In Token Ring,th t t d th t th i l t l d th
8/2/2019 Basic Networking Knowledge
150/183
150
the computers are connected so that the signal travels around the
network from one computer to another in a logical ring.A single electronic token moves around the ring from onecomputer to the next. It simply passes the token on to the nextworkstation till it reaches the computer which wishes to transmitand receives an empty token, it attaches data to the token. Thetoken then proceeds around the ring until it comes to the computerfor which the data is meant.
At this point, the data is captured by the receiving computer. TheToken Ring protocol requires a star-wired ring using twisted pair
or fiber optic cable.It can operate at transmission speeds of 4 Mbps or 16 Mbps.
FDDI
Fiber Distributed Data Interface (FDDI) is a networkprotocol that is used primarily to interconnect two or
8/2/2019 Basic Networking Knowledge
151/183
151
p p y
more local area networks, often over large distances.The access method used by FDDI involves token-passing. FDDI uses a dual ring physical topology.
Transmission normally occurs on one of the rings;however, if a break occurs, the system keepsinformation moving by automatically using portions ofthe second ring to create a new complete ring.
A major advantage of FDDI is speed. It operates overfibre optic cable at 100 Mbps.
Summary Chart:
8/2/2019 Basic Networking Knowledge
152/183
152
Protocol Summary
8/2/2019 Basic Networking Knowledge
153/183
153
RELATIONSHIP BETWEEN
MEDIUM AND TOPOLOGY
The choice of transmission media and topology cannot be
made independently They together decides the reliability
8/2/2019 Basic Networking Knowledge
154/183
154
made independently. They together decides the reliability,
expandability and performance of the network. The topology
used for different media are given by the following table.
MEDIUM TOPOLOGIES
TWISTED-PAIR BUS, RING, STAR
BASEBAND COAXIAL BUS, RING, STAR
BROADBAND COAXIAL BUS, TREE
OPTICAL FIBRE RING, TREE
8/2/2019 Basic Networking Knowledge
155/183
155
Networking Hardware
File Servers
Workstations
8/2/2019 Basic Networking Knowledge
156/183
156
Network Interface Cards Modems
Repeaters
Concentrators/Hubs Transreceivers
Switches
Bridges Multiplexer
Routers
File Servers
A file server stands at the heart of most networks.It is a very fast computer with a large amount of RAM
and storage space, along with a fast network interfacecard
8/2/2019 Basic Networking Knowledge
157/183
157
card.
The network operating system software resides on thiscomputer, along with any software applications and datafiles that need to be shared.
The file server controls the communication of informationbetween the nodes on a network.
For example, it may be asked to send a word processor
program to one workstation, receive a database file fromanother workstation, and store an e-mail message duringthe same time period. This requires a computer that canstore a lot of information and share it very quickly.
Workstations
All of the computers connected to the file serveron a network are called workstations.
8/2/2019 Basic Networking Knowledge
158/183
158
A typical workstation is a computer that isconfigured with a network interface card,networking software, and the appropriate cables.
Workstations do not necessarily need floppy diskdrives or hard drives because files can be saved onthe file server.
Almost any computer can serve as a networkworkstation.
Network Interface Cards
The network interface card (NIC) provides the physical connection between
the network and the computer workstation.
A memory buffer inside the network card grabs massages from the computer
8/2/2019 Basic Networking Knowledge
159/183
159
y g g p
and holds them until the card can send the message through the cable.
Another memory buffer holds messages coming on the network cable until
the computer is ready to read the message
Most NICs are internal, with the card fitting into an expansion slot inside thecomputer.
Network interface cards are a major factor in determining the speed and
performance of a network. It is a good idea to use the fastest network card
available for the type of workstation you are using.
The three most common network interface connections are Ethernet cards,
Local Talk connectors, and Token Ring cards.
Sample Network InterfaceBoards
8/2/2019 Basic Networking Knowledge
160/183
160
Network Interface Board Installations
8/2/2019 Basic Networking Knowledge
161/183
161
Ethernet Cards
8/2/2019 Basic Networking Knowledge
162/183
162
MODEMA modem is a device that converts digital data into analog signal for
transmission over telephone line. It involves modulation at thetransmitting end and demodulation at the receiving end. The same
device can be used to connect remote computers over telephone
8/2/2019 Basic Networking Knowledge
163/183
163
networks.In some instances, modems can take the place of NICs in
connecting a device to a network.
For example, you can dial in to your network from acomputer with a modem, if a modem and phone connection
are available on a device on your network.
The following functions are involved in the management of a modem:-
Dialing
Answering
Disconnecting
Modem Installation
8/2/2019 Basic Networking Knowledge
164/183
164
Repeaters
A repeater is a device that boosts a network'ssignal as it passes through the transmission
8/2/2019 Basic Networking Knowledge
165/183
165
medium by electrically amplifying the signal itreceives and re-broadcasting it.
They are used when the total length of yournetwork cable exceeds the standards set for thetype of cable being used.
Repeater Use
8/2/2019 Basic Networking Knowledge
166/183
166
Repeater Installation
8/2/2019 Basic Networking Knowledge
167/183
167
Concentrators/Hubs
Hubs receive transmissions from connected devices
and transmit the signals to the other connected
8/2/2019 Basic Networking Knowledge
168/183
168
devices. The hub organizes the cables and transmitsincoming signals to the other media segments.
Some network implementations require a centralpoint of connection between media segments. These
central points are referred to as hubs, multiport
repeaters, or concentrators.
Cables from network devices plug in to the ports on
the hub.
An active hub, which connects medium segments
together, regenerates or amplifies signals. Because
they generate signals, active hubs can extend themaximum cable length. All computers connected by
active hubs still receive signals from all other
8/2/2019 Basic Networking Knowledge
169/183
169
computers.
A passive hub, which connects medium segments
together, does not regenerate or amplify signals. It
is not a repeater. The distance limitations on eachsegment connected to a passive hub are different
than those applied to segments connected by active
hubs.
HubInstallation
8/2/2019 Basic Networking Knowledge
170/183
170
Transceivers
A Transceiver is not a repeater . The function of a
i i i l d i h k
8/2/2019 Basic Networking Knowledge
171/183
171
transceiver is to connect a single device to the network.There are four types of transceivers, they are:-
(a)Thick wire transceiver.
(b)Thin co-axial transceiver.
(c)Twisted pair transceiver.
(d)Fibre optic transceiver
Switches
Switches allow you to avoid the congestion
of a shared Ethernet network by permitting
8/2/2019 Basic Networking Knowledge
172/183
172
you to create individual segments. The
improvement in network performance can
be dramatic.
8/2/2019 Basic Networking Knowledge
173/183
173
8/2/2019 Basic Networking Knowledge
174/183
174
Bridges
A bridge is a device that allows you to segment a large
network into two smaller, more efficient networks.
8/2/2019 Basic Networking Knowledge
175/183
175
A bridge extends the maximum distance of your
network by connecting separate network segments.
Bridges selectively pass signals from one segment to
another based on the physical location of the
destination device.
Bridge Operations
Bridges receive all signals on
all segments they are attached
8/2/2019 Basic Networking Knowledge
176/183
176
to. Determine the segment
location of the source and
destination devices for each
signal received.
Retransmit signals whose
source and destination devicesare on different segments out
the port connected to the
destination devices segment.
Bridge Installation
8/2/2019 Basic Networking Knowledge
177/183
177
A transmission media that provides morecapacity than a signal can use. To
efficiently use the entire transmission
Multiplexers
8/2/2019 Basic Networking Knowledge
178/183
178
efficiently use the entire transmissionmedia bandwidth, you can installmultiplexers.
A multiplexer combines two or moreseparate signals on a transmission media
segment.
8/2/2019 Basic Networking Knowledge
179/183
Routers
A router translates information from one
network to another; it is similar to a super
intelligent bridge
8/2/2019 Basic Networking Knowledge
180/183
180
intelligent bridge.
Routers connect two or more logically
separate networks. Each network isidentified by its network address, a logical
name assigned to it.Each network in an internet work must be
assigned a unique network address.
Router Operations
8/2/2019 Basic Networking Knowledge
181/183
181
Routers are typically much moreprocessing intensive than bridges. As aresult, their processing speeds (generally
measured in packets or blocks of data
Routers
8/2/2019 Basic Networking Knowledge
182/183
182
measured in packets or blocks of data forwarded per second) are not usually ashigh.
Routers are capable of much moresophisticated path selection. The decision
to buy a bridge or a router hinges onspecific requirements and the specificnetwork environment.
Router Installation
8/2/2019 Basic Networking Knowledge
183/183
183