This document discusses different types of computer networks and data communication. It describes local area networks (LANs) that connect computers within a small area like a building, metropolitan area networks (MANs) that connect LANs within a city, and wide area networks (WANs) that connect networks across large geographic areas or globally. The basic components of data communication are senders, encoders, a transmission medium, decoders, and receivers. Modes of data transmission include simplex, half-duplex, and full-duplex. Common network topologies are bus, ring, star, and mesh.

1. DATA COMMUNICATION
& NETWORKING

2. COMPUTER NETWORK A system in which a number of
independent computers are linked
together to share data and
peripherals, such as files and printers.
In the modern world, computer
networks have become almost
indispensable.
All major businesses and governmental
and educational institutions make use
of computer networks to such an
extent that it is now difficult to
imagine a world without them.

3. Three very common types of networks include:
1 LOCAL AREA NETWORK (LAN)
It is a network that is confined to a
relatively small area. It is generally
limited to a geographic area such
as a writing lab, school, or building.
Simply the computers connected in
the 100m distance are called Local
Area Network (LAN).

4. 2 METROPOLITAN AREA NETWORK (MAN)
It 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.
Three very common types of networks include:
Routers, switches, and hubs are
connected to create a Metropolitan
Area Network.

5. 3 WIDE AREA NETWORK (MAN)
It connect networks in larger geographic
areas, such as Florida, the United States,
or the world. Dedicated transoceanic
cabling or satellite uplinks may be used
to connect this type of global network.
Three very common types of networks include:
Computer networks exist on various
scales, from links between two
computers in one room to connect
computers in a building or campus to
national and global networks.

6. COMPONENTS OF A DATA COMMUNICATION
Data communication is a process of transferring data electronically
from one place to another. Data can be transferred by using a different
medium.
Diagrammatic Representation of Computer Network/Data Communication

7. 1. Sender
2. Encoder
3. Medium/communication channel
4. Decoder
5. Receiver
The basic components of data communications are:
- It is a device that sends a message.
- It is a device that converts digital signals in a form that can
pass through a transmission medium.
- It is a device that converts digital
signals in a form that can pass through a transmission medium.
- It is a device that converts the encoded signals into digital form.
- It is a device that receives the message. It is also called sink.
Source/Sender Medium Host/Receiver
Diagrammatic Representation of Computer Network/Data Communication
Components of Data Communication

8. MODES OF DATA COMMUNICATION
OR MODES OF NETWORK
Transmission mode means transferring of data between two devices. It
is also known as the communication mode.
Buses and networks are designed to allow communication to occur
between individual devices that are interconnected.
There are three types of Transmission mode:
Transmission mode
2. Half-Duplex mode
1. Simplex mode 3. Full-Duplex mode

9. 1. Simplex Mode
In Simplex mode, the communication is unidirectional, as on a one-way
street. Only one of the two devices on a link can transmit, the other
can only receive. The simplex mode can use the entire capacity of the
channel to send data in one direction.
SIMPLEX
ONE DIRECTION
Simplex Mode of Communication

10. 2. Half-Duplex Mode
In half-duplex mode, each station can both transmit and receive, but
not at the same time. When one device is sending, the other can only
receive, and vice versa.
A is sending, B is receiving
Half-Duplex Mode of Communication
B is sending, A is receiving
Send
Send
Receive
Receive
A B
A B
The half-duplex mode is used in cases where there is no need for
communication in both directions at the same time.

11. 3. Full-Duplex Mode
In full-duplex mode, both stations can transmit and receive
simultaneously. In the full duplex mode, signals going in
one direction share the capacity of the link with signals
going in other direction, this sharing can occur in two ways:
1.) Either the link must contain two physically separate transmission
paths, one for sending and other for receiving.
2.) Or the capacity is divided between signals traveling in both directions.
Full-duplex mode is used when communication in both directions is
required all the time.
The capacity of the channel, however, must be divided between the two
directions.

12. FULL-DUPLEX
BOTH DIRECTIONS
Full-Duplex Mode of Communication
COMPUTER COMPUTER

13. 4. Synchronous Mode of Communication
Synchronous communication relies on the presence of a clocking
system at both ends of the transmission.
clock
Transmitter
receiver
data
ground

14. 5. Asynchronous Communication
Asynchronous communication sends small blocks of data with many control
bits for error correction, synchronous techniques use large blocks of data
with control bits only at the start and end of the transmission.

15. 6. Parallel Communication
In data transmission, parallel communication is a method of
conveying multiple binary digits (bits) simultaneously.

16. 7. Serial Communication
With serial communication, it conveys only a single bit at a time.

17. NETWORK TOPOLOGY
Think of a topology as a network’s virtual shape or structure. This
shape does not necessarily correspond to the actual physical layout of
the devices on the network.
Network topologies are categorized into the following basic types:
1. Bus 2. Ring
3. Star 4. Mesh
More complex networks can be built as hybrids of two or more of the
basic above topologies.

18. 1. Bus Topology
Bus networks use a common backbone to connect all devices. A single
cable, the backbone functions as a shared communication medium those
devices attach or tap into with an interface connector.
A device wanting to communicate with another device on the network
sends a broadcast message onto the wire that all other devices see, but
only the intended recipient actually accepts and processes the message.

19. 2. Ring Topology
In a ring network, every device has exactly two neighbors for
communication purposes.

20. 3. Star Topology
Many home networks use the star topology. A star network features a
central connection point called a “hub node” that may be a network hub,
switch or router.
Devices typically connect to the hub with Unshielded Twisted Pair (UTP)
Ethernet.
Unshielded Twisted Pair (UTP)

21. 4. Mesh Topology
Mesh Topology introduces the concept of routes.

22. SEATWORK