The OSI Reference Model
33
F I G U R E 2 . 1
OSI layer communication scheme
The OSI template defines the services and roles that each layer is to pro-
vide. Because each layer provides different services and functions, the layers
need to communicate so that the data can be transmitted up and down
the seven layers and onto the destination system. The following list summa-
rizes the responsibility of each of the seven layers, starting from the Appli-
cation layer and working down to the Physical layer:
Application
This is the user and application interface. The Application
layer is responsible for data exchange and job management. It also han-
dles file, print, message, database, and application services.
Presentation
This layer negotiates syntax, so it is responsible for the
proper method of presenting the data to the Application layer. Some of
the functions are compression and decompression, and encryption and
decryption of data.
L
Copyright ©2000 SYBEX , Inc., Alameda, CA
www.sybex.com