- has seven layers
- each layer provides a set of actions to the layer above and relaies on the functions of the layer below
- each layer communicates with it’s peer layer on another node by sending messages back and forth
task of layer a is defined by set of functions
The OSI Reference Model :
General Principle –
The osi model distinguished betweent
1. Services(Actions)
a. what the layer dosen’t know how it’s accessed.
2. Interface
a. how adjacent layers are not access that layer.
3. Protocol
a. the rule by which peer layer on different nodes communicate.
4. Decisions on the types of layers required and their services
a. each layer should perform a well defined service.
b. the layer boundries should be chosen to minimize the information flow across boundries.
5. Decisions on the number of layers
a. layer should be large enough to avoid grouping together unrelated functions.
