ORACLE 11G Load Balancing test

In the

Oracle 11g R2, the features of the scan (single Client Access Name) are introduced. The advantage of this feature is that between the database and the client, added a layer of virtual service layer, is called the scan IP and scan IP Listener, in the client only need to configure the scan IP TNS information, through the scan IP Listener, connected to the background cluster database. This will not affect the client regardless of whether the cluster database has operations to add or remove nodes.
the process by which clients connect to a DB instance via scan IP is: client---scan listener, local listener, local instance
There are 2 ways to use Scan:
1, Define the domain name in DNS.
2, DHCP customization is implemented through the Oracle-provided grid naming Server (GNS).
If you do not want to use the above 2 methods, you can modify the hosts file of 2 servers, add scan-cluster.localdomain    172.16.0.75. This approach is not recommended by Oracle because this method can only define one SCAN IP.
Load Balancing:
On the server side, remote_listener default is set to scan Listener
on the client, Tnsnames.ora is configured as follows:
RAC =
(DESCRIPTION =
    (ADDRESS = (PROTOCOL = TCP) (HOST = Scan-cluster.localdomain) (PORT = 1521))
   (Connect_data =      (SERVER = dedicated)
      (service_name = RAC)
  ))  

Client connection mode
$ sqlplsu/@RAC
Ezconnet Connection still applies to scan
$ sqlplus/@scan-cluster.localdomain:1521/rac

ORACLE 11G load Balancing test