Technical data

3.1 ISO/OSI Reference Model for Communication
To obtain a structured architecture, the communications tasks were divided
into seven layers (refer to Fig. 3.1). Each device (station) within the network
has the same structure. The layers are hierarchical and each layer provides
a series of services to the next higher layer. With each service, the
executing layer of the local station communicates with the peer layer of the
remote station (logical data exchange). This communication uses a virtual
link with a protocol for the specific layer.
LAYER
TASK
7
6
5
4
3
2
1
Application Layer
Presentation Layer
Session Layer
Transport Layer
Network Layer
Data Link Layer
Physical Layer
Interface to application process,
provides basic functions
Negotiation of the coding of the data
to be transmitted,
transformation of local into transfer syntax
Control of the communication,
Synchronization
Non network-dependent transport service
flow control, fragmentation,
separation of application from the
Routing of traffic within the network,
establishment and termination of links
Distribution, flow control,
error detection and correction
Transmission and reception of unstructured
bit streams, electrical representation of signals
transport links
relevant for CP communication in this volume
Fig. 3.1 The Seven Layers of the ISO/OSI Reference Model
Fundamentals of the Model B8976060/02
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