16.4 Troubleshooting Suggestions for Oracle Net Services

These are the suggestions for diagnosing network problems and troubleshooting Oracle Connection Manager in Traffic Director Mode.

• Suggestions for Diagnosing Network Problems
  These suggestions may be useful when diagnosing and resolving network connectivity errors.
• Troubleshooting Oracle Connection Manager in Traffic Director Mode
  Learn how to resolve errors that you may encounter while executing SELECT statements using Oracle Connection Manager in Traffic Director Mode.
• Questions to Consider When Troubleshooting Oracle Net Services
  These questions help you in diagnosing network problems.

16.4.1 Suggestions for Diagnosing Network Problems

These suggestions may be useful when diagnosing and resolving network connectivity errors.

• Use the node or network address during configuration instead of the name of the server computer. This eliminates any internal lookup problems and make the connection slightly faster.

• If you are using TCP/IP addresses, then use the IP address rather than the host name. For example, change the HOST=server_name line in the tnsnames.ora file to the IP address, such as HOST=192.0.2.5.

• Perform a loopback test on the server as described in Task 2, "Perform a Loopback Test". If the test passes, then use FTP to send the tnsnames.ora and sqlnet.ora files to the client.

• Check the systems between the client and the server. If it is a wide area network (WAN), then identify any intermediate systems that may not work correctly. If all computers are fine, then the problem may be a timing issue.

• Verify whether there is a timing issue. Timing issues are associated with an ORA-12535 error in the client log files.

  To resolve a timing issue, try speeding up the connection by using exact addresses instead of names and increase the INBOUND_CONNECT_TIMEOUT_listener_name parameter in the listener.ora file. The default value for this parameter is 10 seconds.

• Determine which Oracle applications are failing. SQL*Plus may work, but CASE tools may not. If you determine the problem is a data volume issue, then try to transfer a large (5 MB) file with the base connectivity.

16.4.2 Troubleshooting Oracle Connection Manager in Traffic Director Mode

Learn how to resolve errors that you may encounter while executing SELECT statements using Oracle Connection Manager in Traffic Director Mode.

If an application runs a SELECT statement using Oracle Connection Manager in Traffic Director Mode, then the ORA-24449 error message may appear in the following scenarios:

• If you modify data type or maximum length of a select list column on the database server side while Oracle Connection Manager is running.

  To resolve the error, applications need to close or return the SELECT statements and run the query again.

• If you select columns with different formats (for example, TO_CHAR(<datecolumn>) with different NLS_DATE_FORMAT values) and modify the session property either in the same connection or with different connections having different format settings, using Proxy Resident Connection Pooling (PRCP).

  To resolve the error, use column aliases to distinguish statements in the same connection. For PRCP connections, use connection classes or tags.

16.4.3 Questions to Consider When Troubleshooting Oracle Net Services

These questions help you in diagnosing network problems.

• Do all computers have a problem, or is it just one?

  If one computer works and another does not, and the same software (Oracle and third-party products) is installed on each computer, then, if possible, swap out the network cables to see if the problem occurs on the second client. If it does occur, then it indicates that the problem has something to do with the client/server connection and is not local to the client.

• What kind of connections exist between the client and the server, for example, X.25, ISDN, or leased line?

  Sniffers and LAN analyzers are useful for locating intermittent connection failures, and detecting time outs and resent packets. You can also see which side is waiting for a response.