This document discusses various concepts related to data transmission and computer networks. It covers topics such as transmission of data, protocols and handshaking, different types of networks including LANs and WANs, common network topologies, and network access methods. It also describes various hardware components used in networks such as NICs, servers, routers, switches, and transmission media. Finally, it discusses network software concepts like network operating systems and their tasks as well as intranets and extranets.

1. Transmitting & Receiving
In Communication
Systmems

2. Communication Concepts
• Transmission of data
• Protocols & Handshaking
• Networks
• LANs & WANs
• Topologies
• Network Access Methods

3. Transmission of Data
• Data Transmission is the physical
transfer of data (sending and receiving)
over a point-to-point or point-to-
multipoint communication channel.
• In order for data transmission to occur,
there must be a transmission line, also
called transmission channel or channel,
between the two machines.

4. Protocols & Handshaking
• Protocol- A communications protocol
defines the rules for sending blocks of
data (each known as a Protocol Data
Unit (PDU)) from one node in a
network to another node
• Handshaking- It is usually a process
that takes place when a computer is
about to communicate with a foreign
device( e.g. a modem, printer, or
network server) to establish rules for
communication.

5. Networks
• A network is a group of two or more
computer systems linked together.
There are many types of computer
networks, including:
• Local-area networks (LANs)
• Wide-area networks (WANs)
Below are different networks:

6. LANs & WANs
• Local-area networks (LANs) : The
computers are geographically close
together (that is, in the same building).
• Wide-area networks (WANs) : The
computers are farther apart and are
connected by telephone lines or radio
waves.

7. Topologies
• Star Topology : Where a central unit
provides a link through which a group
of smaller computers and devices is
connected
• Bus Topology : Each computer in the
network is responsible for carrying out
its own communications without the aid
of a central unit.
• Ring Network : Each computer is
connected to the next two other
computers in a closed loop.

8. Network Access Methods
• The set of rules that defines how a
computer puts data onto the network
cable and takes data from the cable is
called an access method. Once data is
moving on the network, access methods
help to regulate the flow of network
traffic.

9. Network Hardware
• NICs
• Servers
• Routers & Switches
• Bridges & Gateways
• Hubs
• Transmission Media

10. NICs
• A network interface card (NIC),
commonly referred to as an Ethernet
card and network, is a computer
circuit board or card that is installed in
a computer so that it can be connected
to a network.

11. Servers
• A server is a computer program that
provides services to other computer
programs (and their users) in the same
or other computers.
• For example a web server serves up
web pages.

12. Routers & Switches
• Router : A device that forwards data
packets along networks. A router is
connected to at least two networks,
commonly two LANs or WANs.
• Switches: In networks, a device that
filters and forwards packets between
LAN segments

13. Bridges & Gateways
• Bridge: A connecting device which has
it’s own processor, memory and two
NIC cards, to connect two portions of a
network. Facilitates host to host
communication
• Gateway: A data communication
device that provides a remote network
with connectivity to a host network

14. Hubs
• A hub is a connection appliance which
allows communication to flow between
multiple segments of a LAN. A hub
connects computers so that data or
packets of information can be shared.
• A hub usually includes a switch and
sometimes a router.

15. Transmission Media
• Transmission media is the physical
system used to carry a communication
signal from one system to another.
• There are many different types of
transmission media, the most popular
being twisted-pair wire (normal
electrical wire), coaxial cable (the type
of cable used for cable television), and
fiber optic cable (cables made out of
glass).

16. Network Software
• NOSs
• Network Operating System Tasks
• Logon & Logoff Procedures
• Intranet & Extranet

17. NOSs
• Network Operating System, also
referred to as the Dialoguer, is the
software that runs on a server and
enables the server to manage data,
users, groups, security, applications,
and other networking functions.

18. Network Operating System Tasks
• Network Operating System are
designed to allow shared file and
printer access among multiple
computers in a network.
• E.g. of popular network operating
systems include Microsoft Windows
Server 2003/2008.

19. Intranet & Extranet
Intranets and extranets are
communication tools designed to enable
easy information sharing within
workgroups.
• Intranet: The generic term for a
collection of private computer
networks within an organization.
• Extranet: A computer network that
allows controlled access from the
outside for specific business or
educational purposes.

20. THE END