This illustration depicts the layers of stack communication used in an initial connection. On the client side, from the top down, the stack includes 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 includes the following layers:
Listener and RDBMS
Oracle Net Foundation Layer
Oracle Protocol Support
Network Protocol (TCP/IP, TCP/IP with SSL, and Named Pipes)