The client of a Oracle Database Server (SAP Instance) connects to Oracle Database Server over network using the protocol TCP/IP and top of it Oracle Net software layer will be used. The work process of SAP Instance configured on the Oracle Database Server to use the IPC protocol Named pipes to communicate with dedicated shadow processes on the same server.

Both Application Server and Database Server consists of Oracle Network Services (Oracle Net) for establishing and maintaining the connection, as well as for exchanging messages between them, using TCP/IP protocol.

Oracle Net Listener is a special process available on the Oracle database server whose responsible is to listen for incoming connection requests from SAP Instance. The listener forwards this request to Oracle database server by checking client information in the listener file. Once a connection is established, the SAP Instance and Oracle database server communicates directly with one another.

listener.ora file is responsible for checking protocol address, host name, port and default tracing information of client which is requesting connection to the Oracle database server, to establish connection between SAP instance and Database server.

tnsnames.ora file contains a list of service names for all databases that can be accessed over the network.

sqlnet.ora can contain client side information such as client domain to append to unqualified service names or net service names, or optional diagnostic parameters used for client tracing and logging.

All of the above three files are located in the directory ORACLE_HOME/network/admin.

The listener must be running for Oracle Net to accept connections on the Oracle Database server. lsnrctl tool will be used to start and stop the listner and also it will be used for checking the status of the listener. When the listner is started, The service Oracle<DBSID><Release>TNSListener will be started on the Windows Server.

Following are the screen shots of starting LSNRCTL, list of available listener commands and the status of listener. The listener can be pinged using the Oracle command TNSPING. The screenshot of result of TNSPING also provided below.

Connection between SAP Instance and Oracle Database Server

LSNRCTL Oracle Utility, its available commands and status

Successful result of TNSPING

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