Oracle errors can sometimes involve mistakes in connecting between two points in a network. These sorts of network connectivity issues are ubiquitous across all network-driven database programs. Fortunately for you, Oracle has made it relatively simple to correct these types of errors in their software. Today, we will discuss how to manage one of these occurrences, the ORA-12545 error.
The cause of an ORA-12545 error is a failed connection. This results from a target host or object not existing in the specified parameters of Oracle. It can also result intermittently when trying to connect to a RAC database, via no connection being achieved or the connection being redirected to the wrong host. This can also occur from the client end, sometimes frequently when working with 10g Standard RAC.
There are several steps you should run through to correct an ORA-12545 error. You should first check to make sure the address is entered properly. Go to the ADDRESS parameters, where it is most likely that the error is coming from an incorrect node name. You should next make sure that the executable for within your server exists (items could be missing from the name, such as “oracle”).
Next, make sure that your listener is running (marked by the lsnrctl stat parameter). If you do not find the error here, try testing the connection in the network. Do this by issuing a simple ping, and then try a tns ping. You can then verify the connection through the DNS by checking the host procedures.
If your protocol for your Oracle database network is TCP/IP (Transmission Control Protocol/Internet Protocol, an end-to-end connectivity specifying how data is packaged and transferred), try editing the TNSNAMES.ORA file. To do this, change the host name to a numeric IP address and reissue the connection. Lastly, you can double-check your tnsnames.ora parameters to see if a mistake was made there. The error should be hidden at one of these steps; stick to the order for the most common causes of the error.
With any network errors, falling back on some steps before even delving into a deep diagnosis is a great strategy. You should always send out a ping to test connectivity. This step can tell an infinite amount about where your problems are stemming from. If you are having further network errors, work with your database administrator to see if the problem is central to just Oracle and not a general network problem. For more information on RAC databases and recurring network errors, consider contacting a licensed Oracle consultant to help assist your company with managing its needs.