The session layer is also called the communication control layer. It relieves the communi-
cation between service deliverer and the requestor by establishing and holding the con-
nection if the transport system has a short time fail out. At this layer, logical users may
communicate via several connections at the same time. If the transport system fails, a
new connection is established if needed. Additionally this layer provides methods for con-
trol and synchronization tasks.
This layer manages the presentation of the messages, when different network systems
are using different representations of data. Layer 6 converts the data into a format that is
acceptable for both communication partners. Here compression/decompression and
encrypting/decrypting tasks are processed. This layer is also called interpreter. A typical
use of this layer is the terminal emulation.
The application layer is the link between the user application and the network. The tasks
of the application layer include the network services like file, print, message, data base
and application services as well as the according rules. This layer is composed from a
series of protocols that are permanently expanded following the increasing needs of the
user.
Layer 5 - Session layer
Layer 6 - Presentation
layer
Layer 7 - Application layer
System 300S
+
Deployment Ethernet communication - productive
Basics - ISO/OSI reference model
HB140 | CPU | 315-4PN23 | en | 18-02
102
