Figure 4-5
This illustration depicts the various layers of stack communication used in an initial connection. On the client side, from the top down, the stack is constructed with the following layers:

• Client Application (uses OCI)
• Presentation - TTC
• Oracle Net Foundation Layer
• Oracle Protocol Support
• Network Protocol (TCP/IP, TCP/IP with SSL, and Named Pipes)

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

• Listener and RDBMS
• Oracle Net Foundation Layer
• Oracle Protocol Support
• Network Protocol (TCP/IP, TCP/IP with SSL, and Named Pipes)