You can change the wrapper that you use to access a data source after you upgrade. You might change a wrapper when you want to upgrade for new wrapper functionality.
Version 8.1 supported more than one wrapper for some data sources, such as the SQLNET and NET8 wrappers for Oracle data sources and the DBLIB and CTLIB wrappers for Sybase data sources. Since version 8.2 to today, the SQLNET wrapper is not supported for Oracle data sources and the DBLIB wrapper is not supported for Sybase data sources.
You can change the wrapper by either reissuing all the SQL statements manually, or you can use the db2look command to obtain the correct syntax necessary for each data source configuration statement.