This document describes the seven-layer Open Systems Interconnection (OSI) model for network communication. Each layer has a specific function and communicates with the layers directly above and below it. Published in 1984, the OSI model allows newer technologies to be introduced transparently at any layer. It demonstrates how web browsers can be used across different operating systems and networks.

2.  Watch The Dawn of the Net

3. • Considered an open-standards protocol
• Seven layers to provide networked services
• Each layer has a specific function and must communicate with the layer
above and below it
• Describes the functions for computers to communicate
• Published in 1984 by the International Organization for Standardization
• Because layers only communicate directly with the layer above and
below it, newer technologies are able to be introduced at any layer and
be used transparently by other layers.
•
• Demonstrated when web browsers are able to be used regardless of
operating system or network hardware
p6 (Doherty, Anderson & Maggiora, 2007)

4. The OSI Model Physical
What is it?
Application This layer converts output from layer 2 into
electrical signals that can be transmitted over
Presentation the network.
Session Example
Network cables (CAT 5, CAT 53, CAT 6, and
fiber optic cables are some of the most
Transport common physical representations of networks.
Network For more information
Physical Layer Video
Data Link Citation
p6 (Doherty, Anderson & Maggiora, 2007)
Physical
EDTech 541 Network Project

5. The OSI Model Data Link
What is it?
Application This layer adds a header which identifies the
layer 3 protocol in addition to the destination
Presentation and source hardware address (MAC address)
Session
Example
This layer refers to wireless, local area networks
Transport (LANs), and wide area networks (MANs).
For more information
Network Data Link Layer Video
Citation
Data Link p6 (Doherty, Anderson & Maggiora, 2007)
Physical
EDTech 541 Network Project

6. The OSI Model Network
What is it?
Application This is where most communication layers do
their work. This layer adds a header to the
Presentation beginning of the packet to identify the source
and destination
Session
Example
Transport Routers are responsible for directing network
traffic from a specific location to another
location through packets.
Network
For more information
Network Layer Video
Data Link
Citation
p7 (Doherty, Anderson & Maggiora, 2007)
Physical
EDTech 541 Network Project

7. The OSI Model Transport
What is it?
Application This layer takes data from the application and
breaks it into smaller pieces and adds a
Presentation header to identify the sending/receiving
application. These pieces of data along with
their headers are called packets.
Session
Example
HTTPS and SSL are often seen when shopping
Transport online or engaging in secure transactions.
For more information
Network Transport Layer Video
Citation
Data Link p7 (Doherty, Anderson & Maggiora, 2007)
Physical
EDTech 541 Network Project

8. The OSI Model Session
What is it?
Application This layer is responsible for managing
connections between hosts.
Presentation
Example
Session Video Conferencing (Skype, Google Voice,
WebEx, Go2Meeting). When functioning
properly, this layer allows for the audio and
Transport video to be streamed synchronously.
For more information
Network Session Layer Video
Citation
Data Link p7 (Doherty, Anderson & Maggiora, 2007)
Physical
EDTech 541 Network Project

9. The OSI Model Presentation
What is it?
Application This layer formats the data for the application.
Presentation
Example
Accessing Secure Content. The presentation
Session layer is where encryption and decryption for
secure content occurs. It is his layer which
communicates with the application to display
Transport the data session layer to obtain the data.
For more information
Network Presentation Layer video
Citation
Data Link p7 (Doherty, Anderson & Maggiora, 2007)
Physical
EDTech 541 Network Project

10. The OSI Model Application
What is it?
Application Provides services to a user or an application
Presentation
Example
Sending Email. The application layer takes the
Session data from the email application and prepares
it to be transmitted through the network and
layers 6, 5, 4, 3, 2, and 1
Transport
For more information
The Application Layer
Network
Citation
p7 (Doherty, Anderson & Maggiora, 2007)
Data Link
Physical
EDTech 541 Network Project

11.  While watching The Dawn of the Net, see
if you can identify examples of the seven
layers of the OSI model.
 Ready to apply your skills? Play the OSI
Game
 Find real world examples of the OSI
Model

12. Works Cited
Doherty, J., Anderson, N., & Maggiora, P. (2007). Cisco networking
simplified. (2 ed.). Cisco Press.