Figure 4-2
This illustration depicts the Open Systems Interconnection (OSI) communication layers and where Oracle Net software fits into those layers. On the client side, from the top down, the stack is constructed with the following layers:

- Application Layer
- Presentation Layer
- Session Layer (Oracle Net)
- Transport Layer
- Network Layer
- Data Link Layer
- Physical Layer

On the server side, from the top down, the stack is constructed with the following layers:

- RDBMS
- Presentation Layer
- Session Layer (Oracle Net)
- Transport Layer
- Network Layer
- Data Link Layer
- Physical Layer