CPE401_MODULE1_Data_Communication_and_Networking.pdf

Data communication and Network Slides(Professor Oluwaranti)

1. CPE401
Data Communications & Computer Networks
Prof. A. I. Oluwaranti
[email protected]
Slides developed from Data Communications and Networking. Forth Edition. By Behrouz A. Forouzan and other online materials
Module 1:

2. Learning Objectives
•Understand the historical overview of communications,
information systems and the Internet
•Describe the various applications of data
communications networks
•Understand the major components of and types of
networks
•Understand the role of network layers
•Distinguish the role of network standards
•Describe three key trends in communications and
networking
2

3. Recommended Textbooks:
•Data Communications and Networking. Forth Edition.
By Behrouz A. Forouzan
•Digital Network by Andrew Tanenbaum
•Internet Core Protocol. A Definitive Guide By Eric A.
Hall

4. Relevance of the Course
•This Course has revelance as the basic foundation
for:
•Wireless Networks
•Mobile Communication
•Cloud Computing
•Cyber Security
•Web Technologies
•Internet of Things (IoT)
•And several other sub-specialities

5. A Brief History of Communications
•In the Industrial Revolution, machines transformed
work and new organizational forms came into
existence.
•The use of computers and data communications
networks has been termed the ‘second industrial
revolution’, because it is revolutionizing the way
people work and communicate.
•One such factor is the information lag:
•In the 19thcentury, information that took days or weeks to be
transmitted long distances.
•In the early 20thCentury, it took minutes or hours.
•Today, telecommunications networks transmit huge quantities of
information in a fraction of a second.

6. Chronology of Internet Evolution(W. Stallings)
•1966ARPA packet-switching experiment
•1969First ARPANET nodes operational
•1972Distributed e-mail invented
•1973Non-US computer linked to ARPANET
•1975ARPANET transitioned to Defense
Communications Agency
•1980TCP/IP experiment began
•1981New host added every twenty days
•1983TCP/IP switchover complete

7. Chronology of Internet Evolution continued
•1986NSFnet backbone created
•1990ARPANET retired
•1991Gopher introduced
•1991WWW invented
•1992Mosaic introduced
•1995Internet backbone privatized
•1996OC-3

8. Growth of the Internet
•Exponential growth in the 1990s (Web technology
is a major factor)
•More than 30-million computers were attached to
the Internet in 1998
•Doubling the size every 9 to 12 month in the 1990s

9. Growth of the Internet (contd)

10. The original ARPANET design

11. Growth of the ARPANET. (a) Dec. 1969. (b) July 1970.
(c) March 1971. (d) April 1972. (e) Sept. 1972.

12. The NSFNET backbone in 1988.

13. Datacom Definition
•Thetermtelecommunicationmeanscommunicationata
distance.Theworddatareferstoinformationpresentedin
whateverformisagreeduponbythepartiescreatingandusing
thedata
•Datacommunicationsaretheexchangeofdatabetweentwo
devicesviasomeformoftransmissionmedium;beitwiredor
wireless.
•Fordatacommunicationstooccur,thecommunicatingdevices
mustbepartofacommunicationsystemmadeupofa
combinationofhardware(physicalequipment)andsoftware
(programs).
13

14. Datacom Basics
•The effectiveness of a data communications system
depends on four fundamental characteristics:
•Delivery
•must deliver data to the correct destination. Data must be received by the
intended device or user and only by that device or user
•Accuracy
•must deliver the data accurately. Data that have been altered in
transmission and left uncorrected are unusable
•Timeliness
•must deliver data in a timely manner. Data delivered late are useless
•Jitter
•refers to the variation in the packet arrival time. It is the uneven delay in
the delivery of audio or video packets

15. Components of a Datacom System
There are five (5) Data Communication System
1.Message
•the information (data) to be communicated. Popular forms of
information include text, numbers, pictures, audio, and video.
2.Sender
•The sender is the device that sends the data message. It can be a
computer, workstation, telephone handset, video camera, and so on.
3.Receiver
•The receiver is the device that receives the message. It can be a
computer, workstation, telephone handset, television, and so on.

16. Components of a Datacom System (contd)
4.Transmission medium
•The transmission medium is the physical path by which a message
travels from sender to receiver. Some examples of transmission media
include twisted-pair wire, coaxial cable, fiber-optic cable, and radio
waves.
5.Protocol.
•A protocol is a set of rules that govern data communications. It
represents an agreement between the communicating devices.
This relationship is illustrated in Figure 1

17. Figure 1 Components of a data communication system

18. Data Representation
Data/Information today comes in different forms
such as:
•text ASCII, EBCDIC, Unicode
•Why is Unicode important in Data Communications?
•a / A???
•Numbers
•Images.
•audio,
•video.

19. Communication Data Flow
•Communication between two devices can be:
•Simplex
•Flow in one direction only
•half-duplex
•Flow in both direction but not simultaneously
•full-duplex
•Simultaneous flow in both direction
•This is shown in Figure 2.

20. Figure 2 Data flow (simplex, half-duplex, and full-duplex)

21. Computer Networks
•Anetworkisasetofdevices(oftenreferredtoas
nodes)connectedbycommunicationlinks.
•Anodecanbeacomputer,printer,oranyother
devicecapableofsendingand/orreceivingdata
generatedbyothernodesonthenetwork.
•Alinkcanbeacable,air,opticalfiber,oranymedium
whichcantransportasignalcarryinginformation.
•Distributed Processing
•Most networks use distributed processing, in which a task
is divided among multiple computers.

22. Network Criteria
A network must be able to meet a certain
number of criteria. The most important of these
are: Performance, Reliability and Security
•Performance
•Depends on Network Elements.
•Measured in terms of Throughput and Delay
•Are these terms contradictory?

23. Network Criteria (contd)
•Reliability
•Failure rate of network components
•Measured in terms of availability/
robustness
•Security
•Data protection against corruption/loss of
data due to:
•Errors
•Malicious users

24. Physical Structure of a Network
•TypeofConnection
•Anetworkistwoormoredevicesconnected
throughlinks.
•Alinkisacommunicationspathwaythattransfers
datafromonedevicetoanother.
•Forcommunicationtooccur,twodevicesmustbe
connectedinsomewaytothesamelinkatthe
sametime
•Therearetwopossibletypesofconnections:
•point-to-point
•multipoint.

25. Point-to-point connection
•Apoint-to-pointconnectionprovidesa
dedicatedlinkbetweentwodevices.
•Theentirecapacityofthelinkisreservedfor
transmissionbetweenthosetwodevices.
•Mostpoint-to-pointconnectionsuseanactual
lengthofwireorcabletoconnectthetwo
ends,
•otheroptions,suchasmicrowaveorsatellite
links,arealsopossible(seeFigure3a).

26. Multipoint connection
•A multipoint (also called multidrop) connection
is one in which more than two specific devices
share a single link (see Figure 3b).
•In a multipoint environment, the capacity of
the channel is shared, either spatially or
temporally.
•If several devices can use the link
simultaneously, it is a spatially shared
connection.
•If users must take turns, it is a timeshared
connection.

27. Figure 3 Types of connections: point-to-point and multipoint

28. •Network topology refers to the way in which a
network is laid out physically
•Two or more devices connect to a link; two or
more links form a topology
•The topology of a network is the geometric
representation of the relationship of all the
links and linking devices (usually called nodes)
to one another.
Network Topology

29. Network Topology (contd)
•There are four
basic topologies
possible:
•Mesh
•Star
•Bus
•Ring
Figure 4:NetworkTopologies

30. Figure 5 A fully connected mesh topology (five devices)

31. Figure 6 A star topology connecting four stations

32. Figure 7 A bus topology connecting three stations

33. Figure 8 A ring topology connecting six stations

34. •Type of Connection
•Point to Point -single transmitter and
receiver
•Multipoint -multiple recipients of single
transmission
•Physical Topology
•Connection of devices
•Type of transmission -unicast, mulitcast,
broadcast
1.34
Physical Structures

35. 1.35
Figure 1.9 A hybrid topology: a star backbone with three bus networks

36. Summary
•Datacommunicationsarethetransferofdatafromone
devicetoanotherviasomeformoftransmission
medium.
•Adatacommunicationssystemmusttransmitdatato
thecorrectdestinationinanaccurateandtimely
manner.
•Thefivecomponentsthatmakeupadata
communicationssystemarethemessage,sender,
receiver,medium,andprotocol.
•Text,numbers,images,audio,andvideoaredifferent
formsofinformation.

37. Summary(Contd)
•Dataflowbetweentwodevicescanoccurinoneofthreeways:simplex,half-duplex,orfull-duplex.
•Anetworkisasetofcommunicationdevicesconnectedbymedialinks.
•Inapoint-to-pointconnection,twoandonlytwodevicesareconnectedbyadedicatedlink.Inamultipointconnection,threeormoredevicessharealink.
•Topologyreferstothephysicalorlogicalarrangementofanetwork.Devicesmaybearrangedinamesh,star,bus,orringtopology.