DATA COMMUNICATION BY IQBAL SIR

1. Overview of
Data Communications
IQBAL Ahmed, PhD
PhD (Japan), MSc (PERCCOM, France) BSc (CU, Bangladesh)
Professor, Dept. of Computer Science & Engineering
Member, Research & Publication Cell, CU
Member, Innovation Team, CU
Mobile: +8801711481086
E-mails: iqbal.ahmed@cu.ac.bd; iahmed077@gmail.com

2. Data : refers to facts, concepts and instructions presented
in whatever agreed upon by the parties creating and using
data.
Data Communication : is the exchange of data
(in the form of 0’s and 1’s) between two devices via some
form of transmission medium (such as wire, cable etc).
Overview

3. Overview

4. The effectiveness of a data communication system depends
on three fundamental characteristics:
 Delivery : The system must deliver data to the correct
destination.
 Accuracy : The system must deliver data accurately.
 Timeliness : The system must deliver data in a timely
manner.
Overview

5. Chapter 1
Introduction

6. Data Communication
Components
Data Representation
Direction of Data Flow

7. Five components of data communication
 Message
 Sender
 Receiver
 Medium
 Protocol

8.  Transmission Mode
is used to define the direction of signal flow between
two linked devices.
 Line Configuration
refers to the way two or more communicating devices
attach to a link.
Direction of Data flow

9. Simplex
 Simplex Transmission Mode
In simplex mode the communication is
unidirectional. e.g. keyboard, monitor etc.

10. Half-duplex
 Half duplex Transmission Mode
each station can both transmit and receive
but not at the same time.
Example: Walkie-Talkies, CB (Citizen’s Band) radio.

11. Full-duplex
 Duplex Transmission Mode
both station can transmit and receive
simultaneously (at the same time).
Example: Telephone, Mobile.

12. Networks
Distributed Processing
Network Criteria
Networks Applications
Categories of Networks

13. Line Configuration
 Point to Point
A P to P line configuration provides a
dedicated link between two devices.

14. Line Configuration
 Multipoint
A multipoint line configuration is one in
which more than two specific devices share a single
link.

15. Categories of topology
 Topology
Topology refers to the way a network is laid
out, either physically or logically. Two or more
devices connect to a link; two or more link form
topology.

16. Fully connected mesh topology
 Mesh
every device has a dedicated point to point link to every
other device.

17. Advantages:
 dedicated link guarantees each connection, carry own load.
 robust, if one link fails then it doesn’t make any effect.
 privacy or security as dedicated link.
 fault identification and isolation is easier.
Advantages & Disadvantages of Mesh
Disadvantages:
 huge amount of cabling.
 huge number of I/O ports required.
 costly
 accommodation problem because of huge cabling.

18. Star topology
 Star
each device has a dedicated point to point link only to
central controller, usually called a hub. The devices are not
directly connected to each other.

19. Advantages:
 less expensive than mesh.
 robust, if one link fails only that link is affected, others remain active.
 easy to install and reconfigure.
Advantages & Disadvantages of Star
Disadvantages:
 if the central device fails, the whole system collapse.
 more cabling than other topologies.

20. Bus topology
 Bus
bus topology is multipoint. One long cable act as a
backbone to link all the devices in the network.

21. Advantages:
 ease of installation.
 less cabling than mesh, star or tree.
Advantages & Disadvantages of Bus
Disadvantages:
 difficult to add new devices.
 difficult reconfiguration and fault isolation.
 a fault or break in the bus stops all transmission.

22. Ring topology
 Ring
each devices has a dedicated p to p link only with the two
devices on either side of it. A signal is passed along the ring in one
direction, from device to device, until it reaches destination.

23. Advantages:
 easy to install and reconfigure.
 to add or delete a device requires moving only two connections.
 fault identification easy.
Advantages & Disadvantages of Ring
Disadvantages:
 unidirectional traffic can be a disadvantages.

24. Categories of networks

25. LAN

26. LAN (Continued)
Topology ??

27. MAN

28. WAN

29. The Internet
A Brief History
The Internet Today

30. Internet today

31. Protocols and Standards
Protocols
Standards
Standards Organizations
Internet Standards

32. Book References :
1.Data Communications and Networking
B. A. Forouzan
2. Data & Computer Communications
Stallings
3. Computer Networking
Andrew S. Tanenbaum
4. Class Lecture
5. Google

33. Distributed Processing
-- in which a task is divided among multiple computers
Advantages :
 Security
 Distributed Database
 Faster problem solving, multiple computers works on parts of
a problem
 Security through redundancy, as multiple computers running
the same program at the same time
 Collaborative Processing, multiple users may interact on a
single task

34. Network Criteria
-- for an effective & efficient network, it must meet 03 criteria
1. Performance
2. Reliability
3. Security
Performance :
 Number of users
 Type of transmission
medium
 Hardware
 Software
Reliability :
 Frequency of Failure
 Recovery time of
network, after failure
 Catastrophe like fire
earthquake, threft etc.
Security:
 Unauthorized Access
 Viruses

35. Network Applications
 Marketing and sales
 Financial Services
 Manufacturing
 Electronic Messaging
 Directory Services
 Information services
 Electronic Data Interchange (EDI)
like pruchase order, invoices etc.
 Teleconferencing
 Video conferencing
 Cellular telephone
 Cable television