The document discusses data communication and networks, detailing how data is exchanged between devices and the various components of communication systems, including messages, senders, receivers, transmission mediums, and protocols. It explores different network topologies such as mesh, star, bus, and ring, along with their advantages and disadvantages, as well as the categories of networks including LAN, WAN, and MAN. Key characteristics of data communication, including performance and reliability criteria, are also addressed.

1. DATA COMMUNICATION&
NETWORKS

2. DataCommunication
Exchange of data between two or more
devices using some transmission
medium.
Another explanation could be:
Electronic transmission of information
that has been encoded digitally (as for
storage and processing by computers)

3. Components of Data
Communication System
Message (text,image, numbers, audio, video)
Sender(computer, workstation, telephone,
camera etc.)
Receiver
Transmission Medium(twisted-pair,optical
fiber, coaxial cable, radiowaves)
Protocol(set of rules that govern data
communication)

4. Characteristics of Data
Comm.
 Delivery
 Accuracy
 Timeliness

5. Mode of Data
Communications
Simplex (unidirectional)
Half-Duplex (bidirectional)
Full-Duplex(bidirectional)

6. Applications ofNetworks
 Resource Sharing
 Hardware (Computing Resources, Disks, Printers,etc.)
 Software (Application Software)
 Information Sharing
 Easyaccessibility fromanywhere (Files, Databases, etc.)
 Search Capability (WWW)
 Communication
 Email
 Message Broadcasting

7. Network Criteria
Performance:
Transmit Time, ResponseTime,
Throughput
Reliability:
Frequency of failure, Time to recover
Security:
Unauthorized Access, Protecting Data

8. Data Transmission
 Parallel transmission
 Serial Transmission

9. PhysicalTopology
It refers to the way how the network is
laid out physically.
Geometric representation of the
relationship of all the links and linking
devices

10. Advantage and
Disadvantages
 Increased speed, Reduced cost, Improved security,
centralized software management, Electronic mail
 High cost of installation, requires time for
administration, failure of server, cable faults

11. Types of PhysicalTopologies
Mesh Topology
Star Topology
BusTopology
Ring Topology
Tree topology

12. Mesh topology
In mesh topology, every device in the network is
physically connected to every other device in the
network.
In mesh topology every device has a dedicated
point-to-point link to every other device.
The term dedicated means that the link carries
traffic only between two devices it connects.

13. Mesh Topology

14. Advantages
The use of dedicated links guarantees that each
connection can carry its own data load.
Failure of single computer does not bring down
the entire network
Security and privacy over the dedicated link
Easy diagnosis
Disadvantages
Installation and configuration is difficult
Cabling cost is more
The hardware required to connect each link

15. Star topology
All the cables connects from the computer to the
central location called HUB.
Broadcast star network
Resends message to all the connected computers
Switched star network
Sends data to a destination computer

16. Working of star topology
The sending computers send
the data to hub. The hub
sends data to the receiving
computer. Each computer in
star network communicates
with a central hub.

17. Star Topology

18. Advantages
Easy to install and wire.
No disruptions to the network when connecting or
removing devices.
Easy to detect faults and to remove parts.
Single computer failure does not broke down the whole
network.
Disadvantages
If the central hub fails , the whole network fails to
operate.
The cabling cost is more.
It require a large length of cable to connect
computers.

19. Bus Topology:
A bus topology is
a topology for a Local
Area Network (LAN) in which
all the nodes are connected to
a single cable. The cable to
which the nodes connect is
called a "backbone".

20. Bus Topology
Signal travels along the backbone
Nodes are connected to the bus cable by
drop lines and taps.
Drop line is a connection running between
the device and the main cable
In this topology, at any instant, only one
computer acts as master and it is allowed to
transmit(broadcast). Other devices are
supposed to listen

21. Bus Topology:

22. Bus Topology

23. Advantages
It is simple and easy to use.
It require a small length of cable to connect
computers.
It is less expensive.
It is easy to extend a bus.
Disadvantages
It is difficult to troubleshoot.
It only supports small number of computers.
The network slow down if the numbers of
computers is increases.
Bus topology is not great for large networks.
Terminators are required for both ends of the main
cable.

24. Ring Topology
In ring topology, each computer is connected to
the next computer with the last one connected to
the first. Thus, a ring of computers is formed.
In ring topology each node connects exactly two
other nodes
Signal is passed along the ring in one direction,
from device to device until , until it reaches the
destination.
Each device is attached or incorporates or
repeater.

25. Working of ring topology:
 Every computer connected to next computer
in a ring.
Each computer receives message from the
previous computer and transmits it to the next
computer. The message
Flows in one direction. The message is passed
around the ring
Until it reaches the correct destination
computer.

26. Ring topology:

27. Ring Topology

28. Ring Topology
Advantages
1 It is relatively less expensive than a star topology network.
2. In a Ring topology, every computer has an equal access to
the network.
3. Performs better than a bus topology under heavy network
load
4. Ring is relatively easy to install and reconfigure
Disadvantages
1 Failure of one computer in the ring can affect the whole
network.
2. It is difficult to find faults in a ring network topology.
3. Adding or removing computers will also affect the whole
network since every computer is connected with previous
and next computer.

29. Categories of Networks
Network Category depends on its size
Primary categories are:
PAN: within a room
LAN: Covers area < 2miles
WAN: Can be worldwide
MAN: Between LAN & WAN, span 30-100 miles

30. Local Area Network (LAN)
 Privately owned
 Links devices in the same office,
building, or campus
 Simple LAN: 2 PCs & 1 printer in home
or office
 Size is limited to a few kilometers
 Allow resources to be shared
(hardware, software, or data)

31. Local Area Network (LAN)
An isolated LAN connecting 12 computers to a hub in a closet

32. Local Area Network (LAN)
 LAN is distinguished by:
 Size (# users of OS, or licensing restrictions)
 Transmission medium (only one type)
 Topology (bus, ring, star)
 Data Rates (speed):
 Early: 4 to 16 Mbps
 Today: 100 to 1000 Mbps

33. LAN

34. Wide Area Networks (WAN)
 Provides long-distance transmission of
data over large geographic areas
(country, continent, world)

35. Wide Area Networks (WAN)
 Switched WAN
 Backbone of the Internet
 Dialup line point-to-point WAN
 Leased line from a telephone company

36. Wide Area Networks (WAN)

37. WAN

38. Metropolitan Area Networks
(MAN)
 Size between LAN and WAN
 Inside a town or a city
 Example: the part of the telephone
company network that can provide a
high-speed DSL to the customer or
cable TV network

39. MetropolitanArea
Network(MAN)
Designed to extend over the entire city.
It may be asingle network asacable TV
network OR
It may be means of connecting anumber of
LANs into alargernetwork
The main reason fordistinguishing MANs asa
special category is that astandard has been
adopted for them. It is DQDB(Distributed
Queue Dual Bus) or IEEE802.6.

40. Network coverage
 Local Area Networks:
 Used for small networks (school, home, office)
 Examples and configurations:
 Wireless LAN or Switched LAN
 ATM LAN, Frame Ethernet LAN
 Peer-2-PEER: connecting several computers together (<10)
 Client/Server: The serves shares its resources between different
clients
 Metropolitan Area Network
 Backbone network connecting all LANs
 Can cover a city or the entire country
 Wide Area Network
 Typically between cities and countries
 Technology:
 Circuit Switch, Packet Switch, Frame Relay, ATM
 Examples:
 Internet P2P: Networks with the same network software can be
connected together (Napster)