Tuning Oracle Net - Expert Oracle RAC Performance Diagnostics and Tuning - page 334

Database Server

RDBMS

Client Server

Client Application LISTENER

SQLPlus/JDBC SCAN LISTENER

Oracle Net
Foundation Layer

Oracle Net
Foundation Layer

Oracle Protocol
Support

Oracle Protocol
Support

Network Protocol
Support

Network Protocol
Support

DNS Name Resolution

Figure 11-1. User connection

Figure 11-1 illustrates two sides of the configuration: the client server that initiates the configuration and the
database server where the connection is targeted. On both sides of the configuration there are,” several network layers,
which include the “Oracle Net foundation layer (ONFL,” “Oracle protocol support layer,” and the “Transport Protocol
layer.” In the Oracle Net architecture, the connectivity drivers, the ONFL, the protocol layers, and the listeners on the
database server are of primary importance.

Connectivity Drivers
Oracle supports various types of connection methods. The common types of connection interfaces found in the
implementations are the SQL Plus and JDBC (Type 2 and Type 4) drivers.

Oracle Net Foundation Layer (ONFL)
This layer is responsible for establishing and maintaining connection between the client application and the database
server. This layer exists on both the client side and the database server side and performs identical functions on
both ends. Apart from this primary activity, it's also responsible for exchanging messages between the two ends of
the communication channel: the client application, which is the source, and the database server, which is the target.
ONFL performs these tasks using the transparent network substrate (TNS) technology. TNS is a common type of
interface that incorporates the Open Systems Interconnect (OSI) transport and network layer protocols. It enables
peer-to-peer application connectivity. TNS technology is responsible for the following:

• Locating the database server based on the host entries used in the connect descriptor; it uses

the DNS server for name resolution or the DNS/GNS combination if GNS is implemented in a
RAC environment

• How many protocols involved in the connection

• How many interrupt handles that exist between client and database server based on the

capabilities of each