Oracle plenty of timeout entries in log

Question

I just found huge amount of such entries in Oracle log, see below:

***********************************************************************

Fatal NI connect error 12170.

  VERSION INFORMATION:
    TNS for 64-bit Windows: Version 11.2.0.3.0 - Production
    Oracle Bequeath NT Protocol Adapter for 64-bit Windows: Version 11.2.0.3.0 - Production
    Windows NT TCP/IP NT Protocol Adapter for 64-bit Windows: Version 11.2.0.3.0 - Production
  Time: 11-NOV-2021 07:18:15
  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: 60
    nt OS err code: 0
  Client address: (ADDRESS=(PROTOCOL=tcp)(HOST=xxx.yyy.zzz.vvv)(PORT=12345))

There are dozens of entries per day, but database is running for many years and users does not have any complaints. In the mean while we have hundreds of users and several systems are using the same database.

Please help to understand what is going on and where should I search a problem? Is there something wrong on client side or server side?

Answer 1

As per my experience, such an issue caused by network problems. I assume the application you're using just reconnects to the DB again so user don't notice anything.

In the "Client address" you see the IP of a client where the error occurred. Check with the customer or ask the user directly if there was any problems and check his/her network