Wireless networks OSI models of 7

1. Mr . Sathish Kumar . M
Department of Electronics and Communication
Engineering
I’ve learned that people will forget what you said, people will forget
what you did, but people will never forget how you made them feel.
–Maya Angelou

3. A network can be one computer connected to the
Internet, or two or more computers connected to each
other (and possibly to the Internet as well). In
a wireless (Wi-Fi)network, the computers are
connected by radio signals instead of wires or cables.
What is Wireless Networks….?

4. • ISO
 International Standards Organization
• OSI
 Open Systems Interconnect

5. • Introduced in 1978 and revised in 1984.
• Formulates the communication process into
structured layers.
• There are seven layers in the model, hence
the name the 7-Layer model.
ISO-OSI

6. 7. Application
6. Presentation
5. Session
4. Transport
3. Network
2. Data Link
1. Physical
7 LAYERS

8. Physical Layer
 The physical layer of the OSI model defines connector and
interface specifications, as well as the medium (cable)
requirements. Electrical, mechanical, functional, and procedural
specifications are provided for sending a bit stream on a
computer network.

9. Data Link Layer
• Allows a device to access the network to send and receive
messages offers a physical address so a device’s data can be
sent on the network
• Works with a device’s networking software when sending and
receiving messages
• Provides error-detection capability
• Network interface cards
• Ethernet and Token Ring switches
• Bridges

10. Network Layer
• The network layer controls the operation of the subnet,
deciding which physical path the data should take based on
network conditions, priority of service, and other factors.
• To make it easier to manage the network and control the flow
of packets, many organizations separate their network layer
addressing into smaller parts known as subnets. Routers use
the network or subnet portion of the IP addressing to route
traffic between different networks. Each router must be
configured specifically for the networks or subnets that will
be connected to its interfaces.

11. Transport Layer
• Purpose of this layer is to provide a reliable mechanism for
the exchange of data between two processes in different
computers.
• Ensures that the data units are delivered error free.
• Ensures that data units are delivered in sequence.
• Ensures that there is no loss or duplication of data units.
• Provides connectionless or connection oriented service.
• Provides for the connection management.
• Multiplex multiple connection over a single channel.

12. Session Layer
• Session layer provides mechanism for controlling the dialogue
between the two end systems. It defines how to start, control and
end conversations (called sessions) between applications.
• This layer requests for a logical connection to be established on
an end-user’s request.
• Any necessary log-on or password validation is also handled by
this layer.
• Session layer is also responsible for terminating the connection.
• This layer provides services like dialogue discipline which can be
full duplex or half duplex.
• Session layer can also provide check-pointing mechanism such
that if a failure of some sort occurs between checkpoints, all data
can be retransmitted from the last checkpoint.

13. Presentation Layer
• The presentation layer, is responsible for how an application
formats the data to be sent out onto the network. The
presentation layer basically allows an application to read (or
understand) the message.
• Encryption and decryption of a message for security
• Compression and expansion of a message so that it travels
efficiently
• Graphics formatting
• Content translation
• System-specific translation

14. Application Layer
• Application layer interacts with application programs and is
the highest level of OSI model.
• Application layer contains management functions to support
distributed applications.
• Examples of application layer are applications such as file
transfer, electronic mail, remote login etc.

15. TCP/IP Model
Application Layer
Application programs using the network
Transport Layer (TCP/UDP)
Management of end-to-end message transmission,
error detection and error correction
Network Layer (IP)
Handling of datagrams : routing and congestion
Data Link Layer
Management of cost effective and reliable data delivery,
access to physical networks
Physical Layer
Physical Media

16. ThankYou……!