Understanding Network Configuration

A client is any application that connects to Oracle Database to send or retrieve data.

Oracle Net establishes and maintains the connection between the client application and the database over a network, and exchanges messages between them using industry standard protocols.

A service name is a logical representation of a database, which is the way a database is presented to clients.

Oracle Net Listener Configuration/ Listener Configuration:

listener.ora - The default listener configuration file

Default Location of listener.ora file:

$ORACLE_HOME/network/admin/listener.ora
or
/u01/app/oracle/product/11.2.0/dbhome_1/network/admin/listener.ora

Service registration is performed by the listener registration (LREG) process—an instance background process—of each database instance. Dynamic service registration does not require modification of the listener.ora file. On the earlier version, before 12c, service registration is performed by PMON process.

Listener File Elements:

Listener configuration, stored in the listener.ora file, consists of the following elements:

1. Name of the listener
2. Protocol addresses that the listener is accepting connection requests on
3. Database services
4. Control parameters

It is possible to configure multiple listeners, each with unique name, in one listener.ora file. Multiple listener configuration is possible because each of the top-level configuration parameters has a suffix of the listener name or is the listener name itself.

Sample Listener File:

LISTENER=
  (DESCRIPTION=
    (ADDRESS_LIST=
      (ADDRESS=(PROTOCOL=tcp)(HOST=sale-server)(PORT=1521))
      (ADDRESS=(PROTOCOL=ipc)(KEY=extproc))))
SID_LIST_LISTENER=
  (SID_LIST=
    (SID_DESC=
      (GLOBAL_DBNAME=sales.us.acme.com)
      (ORACLE_HOME=/oracle9i)
      (SID_NAME=sales))
    (SID_DESC=
      (SID_NAME=plsextproc)
      (ORACLE_HOME=/oracle9i)
      (PROGRAM=extproc)))


Viewing Listener Configuration:

$ lsnrctl status LISTENER (Listener_name mentioned in the listener.ora file)

Starting and Stopping the Listener:

lsnrctl start LISTENER (Listener_name mentioned in the listener.ora file)
lsnrctl stop LISTENER (Listener_name mentioned in the listener.ora file)

Listener Details in NETMGR

1. Execute the 'netmgr' command as oracle user.

$ netmgr

Then, Oracle Net Manager Window will Appear.

2. Click on the Plus Sign (+) of Local. Then, Click on the Profile to see 'Naming Methods'.

 3. Click on the Plus Sign (+) of Service Name to see 'Service Name' and 'Address' Details.

4. Click on the Plus Sign (+) of 'Listeners' to see 'LISTENER' location and port details.

 5. To configure new listener, click on the Green Plus Sign on the Window. I am configuring the listener 'DEMO' as follows -

6. Click on the 'Next', after write down the 'Net Service Name'. I have written there - 'DEMO'.

7. Select the 'Protocol' and Click on the 'Next'.

8. Write the 'Hostname' and 'Port Number'. Click on the 'Next'.

9. Write the 'Service Name' and Click 'Next'.

10. Click on the 'Test' to test the connection and then 'Finish'.

Listener configuration is finished.

All The Best