Fatal NI connect error 12170

The following information is frequently displayed in the alert of the two nodes in the database of 11.2.0.2:
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Fatal NI connect error 12170.
Version information:
TNS for IBM/aix risc System/6000: Version 11.2.0.2.0-Production
TCP/IP NT Protocol Adapter for IBM/aix risc System/6000: Version 11.2.0.2.0-Production
Oracle Bequeath NT Protocol Adapter for IBM/AIX assume System/6000: Version 11.2.0.2.0-Production
Time: 15-NOV-2012 15:49:33
Tracing not turned on.
Tns error struct:
Ns main err code: 12535

TNS-12535: TNS: operation timed out
Ns secondary err code: 12560
Nt main err code: 505

TNS-00505: Operation timed out.
Nt secondary err code: 0
Nt OS err code: 0
Client address: <unknown>
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Fatal NI connect error 12514, connecting:
(DESCRIPTION = (ADDRESS_LIST = (ADDRESS = (PROTOCOL = TCP) (HOST = db1) (PORT = 1525) (ADDRESS = (PROTOCOL = TCP) (HOST = xx) (PORT = 1525) (LOAD_BALANCE = yes) (CONNECT_DATA = (SERVER = DEDICATED) (SERVICE_NAME = zjcs) (CID = (PROGRAM = oracle) (HOST
= Dbdemo1) (USER = oracle ))))
Version information:
TNS for IBM/aix risc System/6000: Version 11.2.0.2.0-Production
TCP/IP NT Protocol Adapter for IBM/aix risc System/6000: Version 11.2.0.2.0-Production
Time: 15-NOV-2012 16:09:34
Tracing not turned on.
Tns error struct:
Ns main err code: 12564

TNS-12564: TNS: connection refused
Ns secondary err code: 0
Nt main err code: 0
Nt secondary err code: 0
Nt OS err code: 0
11g R1 if the above error message is written to sqlnet. log, 11g R2 will write to alert. log. In fact, this error is normal.
Solution to post metalink:
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Note the time of the client corresponding client connection (s) in the listener log. Here you may find a participant client,
Set of clients or particle applications that are improperly disconnecting causing the timeout errors to be raised and recorder in the database alert log.
You may choose to revert from the new Automatic Diagnostic Repository (ADR) method to prevent the Oracle Net diagnostic details from being written to the alert log (s)
By setting the following Oracle Net configuration parameters:
To revert to Oracle Net Server tracing/logging, set following parameter in the server's sqlnet. ora:
DIAG_ADR_ENABLED = OFF
Also, to back out the ADR diag for the Listener component, set following parameter in the server's listener. ora:
DIAG_ADR_ENABLED _ <listenername> = OFF
-Where the <listenername> wocould be replaced with the actual name of the configured listener (s) in the listener. ora configuration file. For example,
If the listener name is 'listener ', the parameter wocould read:
 
DIAG_ADR_ENABLED_LISTENER =
-Reload or restart the TNS Listener for the parameter change to take effect.