If you have both a local and a remote server running on SAP ASE version 15.x and are upgrading both of them to version 16.0, upgrade the local server first. If you plan to upgrade one server but not the other, upgrade the local server.
SAP does not certify that Component Integration Services running on earlier versions of SAP ASE can connect to later versions. You may encounter errors if an earlier version of SAP ASE maps a proxy table to a later version and if the remote table uses functionality that is unavailable in the earlier version.
SAP certifies that each version of SAP ASE connects to earlier versions through Component Integration Services. Component Integration Services is tested and certified to connect to earlier versions of SAP ASE.