The installation process creates a tnsnames.ora file on each node.

The tnsnames.ora file acts as a repository of net service names. Each net service name is associated with a connect identifier. A connect identifier is an identifier that maps a user-defined name to a connect descriptor. A connect descriptor contains the following information:

• The network route to the service, including the location of the listener through a protocol address

• The SERVICE_NAME parameter, with the value set to the name of a database service

The tnsnames.ora file is located in both the Grid_home\network\admin and Oracle_home\network\admin directories. By default, the tnsnames.ora file is read from the Grid home when Oracle Grid Infrastructure is installed.

With Oracle Clusterware 11g Release 2 and later, the listener association no longer requires tnsnames.ora file entries. The listener associations are configured as follows:

• Oracle Database Configuration Assistant (DBCA) no longer sets the LOCAL_LISTENER parameter. The Oracle Clusterware agent that starts the database sets the LOCAL_LISTENER parameter dynamically, and it sets it to the actual value, not an alias. So listener_alias entries are no longer needed in the tnsnames.ora file.

• The REMOTE_LISTENER parameter is configured by DBCA to reference the SCAN and SCAN port, without any need for a tnsnames.ora entry. Oracle Clusterware uses the Easy Connect naming method with scanname:scanport, so no listener associations for the REMOTE_LISTENER parameter are needed in the tnsnames.ora file.

SQL> alter system set local_listener='(DESCRIPTION=(
ADDRESS_LIST=(ADDRESS=(PROTOCOL=TCP)(HOST=192.168.0.61)(PORT=1521))
(ADDRESS=(PROTOCOL=TCP)(HOST=192.168.0.61)(PORT=2012))))' 
scope=BOTH SID='OCRL1';