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A Demonstration of the Alert Log Timeouts Occur: TNS-12170/TNS-12535/TNS-12560/TNS-00505 (Doc ID 2461900.1)

Last updated on DECEMBER 20, 2023

Applies to:

Oracle Net Services - Version and later
Information in this document applies to any platform.


This document describes how an alert log timeout is triggered when an established connection is abruptly terminated due to a TCP or Network interruption.
This is a common problem with remote Oracle Net clients and this document serves to explain the circumstances that will cause this problem to occur.
Review the following for more information about how to resolve this common problem:
<Note: 1628949.1>   Alert Log Errors: 12170 TNS-12535/TNS-00505: Operation Timed Out


This document describes how and why timeout errors are thrown in the database alert log when a TCP interruption occurs after a remote connection is established.
This is a common problem in environments where firewalls exist and where connections might appear idle for a lengthy period of time due to no activity on the network.
Alert log reporting of these kinds of errors was introduced in 11g.   Oracle has a provided a simple fix for most cases where a firewall with a maximum idle time setting is disrupting client connections.


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In this Document
  Database versions 11g and newer, the following errors might occur in the database alert log:

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