How SQL*Net works
SQL*Net is designed to run on top of an existing network protocol, and is therefore independent of the particular hardware and software being used to implement a network. As long as SQL*Net on both sides of the connection is using the same basic protocol (e.g., TCP/IP, LU6.2 or IPX), it won’t matter to Oracle how the underlying network transports the information. Figure 5.3 shows the relationship between SQL*Net and the underlying network; it illustrates Oracle, SQL*Net, TCP/IP, and physical transport on both sides.
The key here is that connectivity to and from the Oracle database and tools is achieved by using SQL*Net, which presents a consistent interface to Oracle. By utilizing an appropriate protocol adapter (in this case, TCP/IP) on each side, SQL*Net is able to conform to the network protocol in use. SQL*Net creates data packets using the native network protocol, and it does not matter how the network is implemented to actually carry the SQL*Net packets. In fact, SQL*Net does not even know if a network exists, and it is possible to use SQL*Net without any network at all by making an internal connection between a client process and a server running on the same machine.
SQL*Net protocol adapters are available to support a variety of network protocols, including:
- TCP/IP
Probably the most common universal protocol, TCP/IP originated on Unix systems but is now widely supported by a variety of operating systems and network hardware.
- SPX/IPX
This protocol was developed by Novell for use in Netware and is available on a variety of operating systems.
- LU6.2
This protocol was developed by IBM and is widely used in its SNA (System Network Architecture) strategy.
- Named pipes
This protocol is used by Microsoft for Windows networking.
When Oracle is installed, both SQL*Net and one or more supported protocol adapters must be installed. Note that not all protocols are supported on every host operating system. For example, Oracle for Windows NT does not provide a protocol adapter for LU6.2, since this is not a protocol normally supported in a Windows environment.