Download OSI Model - Salim Arfaoui

Each layer has a specific
function.
Application
Presentation
It relies on the layer below
to provide a service.
Please do this for me
Session
Transport
Network
Data Link
Physical
OK It’s Done
or
Sorry I couldn’t
Machine A
Machine B
Application
Application
Presentation
Presentation
Session
Session
Transport
Transport
Network
Network
Data Link
Data Link
Physical
Physical
Boss gives
to assistant
Assistant hands
to boss
Assistant hands
to mailman
Mailman delivers
to assistant
Mailman takes
to post office
Mail system uses many tools to transport
Mailman picks
up at post office
Can you
see the
OSI model?
Each relies on the
person/group below
to provide a service
Order repair parts
Delivery of parts.
No direct horizontal communications!
Boss gives
to assistant
Assistant hands
to boss
(1)
Boss gives
to assistant
(5)
Boss says
wrong part
Assistant hands
to boss
(4)
(3)
Boss tells
to ship
Assistant hands
to boss
(2)
Boss told
wrong part
(6)
Effective horizontal
communications
Order repair parts
Delivery of parts.
Return parts
Resend parts.
No direct horizontal communications!
Order repair parts
Delivery of parts.
Effective Client-Server Interaction
Machine A
Machine B
Application
Application
Presentation
Presentation
Session
Intermediate
Nodes
Transport
Session
Transport
Network
Network
Network
Data Link
Data Link
Data Link
Physical
Physical
Physical
•Proper formatting of the message
address Message type
Information
•Timing transmission of the message
•everyone can’t send at the same time
•Reception of the message
•Detecting and reporting errors in the message
•NOT fixing them
How to properly route
messages
•
•Is the message for me
•Do I forward to someone else
•
Universal Naming of addresses
•All networks don’t name the same
•IP addresses are one “universal” approach
•must have someway to translate
•like higher level languages and machine language