OSI Model
By
Laith Mayyahi
LAYOUT
•
•
•
•
INTRODUCTION
OSI MODEL (7-LAYER)
INTERACTION BETWEEN LAYERS IN OSI MODEL
ENCAPSULATION /DE- ENCAPSULATION IN OSI
MODEL
• ADDRESSING LEVEL
• REFERENCES
INTRODUCTION
• Established in 1947, the International Standards Organization (ISO) is
a multinational body dedicated to worldwide agreement on
international standards. An ISO standard that covers all aspects of
network communications is the Open Systems Interconnection (OSI)
model. It was first introduced in the late 1970s.
• The OSI model is a standardized framework for sub-dividing
communications system functionality and services into separate
layers
OSI MODEL (7-LAYER)
OSI MODEL (7-LAYER)
Layers 1-4 relate to
communications technology.
Layers 5-7 relate to user
applications.
ENCAPSULATION /DE- ENCAPSULATION IN OSI MODEL
Encapsulation: At the transmit side,
Each protocol adds headers to
information it receives from the layer
above it
De-encapsulation: At the receiving
end, the process is reversed, with
headers being stripped off at each
layer.
Transmit
Receiver
Identical message
Identical message
Identical message
Identical message
Identical message
Messages at each sides must be
identically.
Identical message
INTERACTION
BETWEEN
LAYERS IN THE
OSI MODEL
Interaction between layers in the OSI model
Layer-2 Network (Exchange between hop-to-hop)
Replace MAC address between each node
Interaction between layers in the OSI model
Layer-3 Network (Move the packet from network to another)
Check the accessibilities of IP in network with Gateway
ADDRESSING LEVEL
Four types of Addressing:
- Physical Address
( i.e. MAC 07:01:02:01:2C:4B)
- Logical Address
(i.e. IPv4 192.168.0.1)
- Port Address
(i.e. 192.168.0.1:5001)
- Specific Address
(i.e. www.google.com)
1
Request Page from user:
http://www.algonquincollege
.com/
Application
Layers
Translate the http to IP through DNS lookup: encapsulated with
port address related to web application port 80..
get http://www.algonquincollege.com/
--2017-12-24 21:32:44-- http://www.algonquincollege.com/
Resolving www.algonquincollege.com... 54.86.119.60
Connecting to www.algonquincollege.com|54.86.119.60|:80...
connected.
HTTP request sent, awaiting response... 200 OK
Length: unspecified [text/html]
Saving to: ‘index.html.1’
Application
Layers
2
Forward the packet of data to network through IPs network and
check the SYN and ACK of packet to tune the window .. OK it
means complete the Request and response.
get http://www.algonquincollege.com/
--2017-12-24 21:32:44-- http://www.algonquincollege.com/
Resolving www.algonquincollege.com... 54.86.119.60
Connecting to www.algonquincollege.com|54.86.119.60|:80...
connected.
HTTP request sent, awaiting response... 200 OK
Length: unspecified [text/html]
Saving to: ‘index.html.1’
Application
Layers
3
References
1.Computer Networks, Andrew S. Tanenbaum
2.www.cisco.com