The Open Systems Interconnection (OSI) model has many advantages, but it also has a few disadvantages. This model provides a good modular approach to system architecture, although it is purely theoretical.
The OSI model makes a clear distinction between a service, an interface and a protocol. This model is not based on any particular technology, so it works as a generic reference in various system architectures.
On the flip side, the fact that the OSI model is not backed technically means that there is an arbitrary division of the functionality in the various layers. Nevertheless, this is a very useful tool for many network architects in the planning phase.