Sicurezza: OSI
Modern computer networks are designed in a
highly structured way. To reduce their design complexity, most
networks are organized as a series of layers, each one built
upon its predecessor.
The OSI Reference Model is based on a proposal
developed by the International Standards Organization (ISO).
The model is called ISO OSI (Open systems Interconnection)
Reference Model because it deals with connecting open systems
- that is, systems that are open for communication with other
systems.
The OSI model has seven layers. The principles
that were applied to arrive at the seven layers are as follows:
1. A layer should be created where a different
level of abstraction is needed.
2. Each layer should perform a well defined
function.
3. The function of each layer should be chosen
with an eye toward defining internationally standardized
protocols.
4. The layer boundaries should be chosen to
minimize the information flow across the interfaces.
5. The number of layers should be large enough
that distinct functions need not be thrown together in the
same layer out of necessity, and small enough that the
architecture does not become unwieldy.
