4. NETWORKS
Part one

5. OUR AGENDA TODAY WILL BE
What is a network ?.
Data networks.
Networks types.
The OSI model.

6. WHAT IS A NETWORK?!

7. DATA NETWORKS
Businesses needed a solution that would successfully
address the following three problems:
i. How to avoid duplication of equipment and
resources.
ii. How to communicate efficiently.
iii. How to set up and manage a network.

8. BUSINESSES REALIZED THAT
NETWORKING TECHNOLOGY COULD
INCREASE PRODUCTIVITY WHILE
SAVING MONEY.

9. WHAT MAKES UP A NETWORK?
Protocol.
Network interface cards (NICs).
Cable.
Network device.

10. NETWORKS TYPES
LAN.
WAN.
VPN.

11. LAN

12. LAN
LOCAL AREA NETWORK
Operates within a limited geographic area.
High speed data transfer rates.
Full time connectivity to local services
Cabling is primary transmission medium

14. WAN
WIDE AREA NETWORK
Operate over a large geographical area.
Allow access over serial interfaces operating
at lower speeds.
Provide full-time and part-time connectivity.
Connect devices separated over wide, even
global areas.

15. THE OSI MODEL
OPEN SYSTEMS INTERCONNECTION
 It is a way of sub-dividing a data communications
system into smaller parts called Layers.
A layer is a collection of similar functions that
provide services to the layer above it and receives
services from the layer below it.
The reason is dividing anything to smaller parts
make easier for troubleshooting and monitoring.

16. OSI model
7-Application layer
6-Presentation layer
5-Session layer
4-Transport layer
3-Network layer
2-Data link layer
1-Physical layer

17. A GOOD WAY TO REMEMBER THE OSI MODEL
OSI model
7-Application layer
6-Presentation layer
5-Session layer
4-Transport layer
3-Network layer
2-Data link layer
1-Physical layer

18. THE MAIN BENEFITS OF THE OSI
MODEL
Helps users understand the big picture of
networking.
Helps users understand how hardware and
software elements function together.
Makes troubleshooting easier by separating
networks into manageable pieces.
Defines terms that networking professionals can
use to compare basic functional relationships on
different networks.

19. 7-APPLICATION LAYER
OSI model
Application layer
Presentation layer
Session layer
Transport layer
Network layer
Data link layer
Physical layer
It provides an interface for
the end user operating a
device connected to a
network.
 Examples of application layer
functionality include:
 Support for file transfers
 Ability to print on a network
 Electronic mail
 Electronic messaging
 Browsing the World Wide Web

20. 6-PRESENTATION LAYER
OSI model
Application layer
Presentation layer
Session layer
Transport layer
Network layer
Data link layer
Physical layer
 It is responsible for how an
application formats the data to
be sent out onto the network.
 It basically allows an
application to read (or
understand) the message.
 Functions:
 Encryption and decryption of a
message for security.
 Compression and expansion of a
message so that it travels efficiently.

21. 5-SESSION LAYER
OSI model
Application layer
Presentation layer
Session layer
Transport layer
Network layer
Data link layer
Physical layer
This session layer allows
applications functioning
on devices to establish,
manage and terminate a
dialog through a network.
Functions:
 Synchronization of data flow.
 Retransmission of data if it is
not received by a device.

22. 4-TRANSPORT LAYER
OSI model
Application layer
Presentation layer
Session layer
Transport layer
Network layer
Data link layer
Physical layer
 It offers end-to-end
communication between end
devices through a network.
 This layer breaks up the data
into packets from the sending
host and then reassembles it in
the receiver(Segmentation).
 It also is used to insure reliable
data transport across the
network.

23. 3-NETWORK LAYER
OSI model
Application layer
Presentation layer
Session layer
Transport layer
Network layer
Data link layer
Physical layer
 Responsible for routing packets.
 It provides an end-to-end logical
addressing system so that a packet
of data can be routed across
several layer 2 networks
 The Internet Protocol (IP)
addresses make networks easier to
both set up and connect with one
another.
 The main hardware of this layer is
the Router because it works with
IP addresses.

24. 2-DATA LINK LAYER
OSI model
Application layer
Presentation layer
Session layer
Transport layer
Network layer
Data link layer
Physical layer
 Allows a device to access the
network to send and receive
messages.
 Provides error-detection
capability.
 Works with a device’s
networking software when
sending and receiving messages.
 The main device is Switch, it
only understand MAC addresses.

25. 1-PHYSICAL LAYER
OSI model
Application layer
Presentation layer
Session layer
Transport layer
Network layer
Data link layer
Physical layer
 It defines connector and
interface specifications, as well
as the medium(cable)
requirements in order to connect
the network.
 It deals with Zeros and Ones
ONLY, it takes them from the
source to destination through
the medium which is Cables.
 The main devices on this layer is
Hub and Repeater.

27. QUESTIONS?

28. THANK
YOU
Mostafa Hussien