The purpose of this scenario is to show how secure interoperability can occur between different releases simultaneously while using multiple authentication protocols (Security Authentication Service (SAS) and Common Secure Interoperability Version 2 (CSIv2)).
For WebSphere Application Server Version 5.x or later to communicate with a WebSphere Application Server Version 4, Version 5.x or later server must support either SAS or SAS and CSIv2 as the protocol choice. By choosing SAS and CSIv2, the Version 5.x or later server also can communicate with other Version 5.x or later servers that support CSI. If the only servers in your security domain are version 5.x or later, it is recommended that you choose CSI as the protocol because this prevents the SAS interceptors from loading. However, if a chance exists that any server has to communicate with a previous release of WebSphere Application Server, select the protocol choice of SAS and CSIv2.
All previous releases of WebSphere Application Server support the SAS authentication protocol only. No special configuration steps are needed other than enabling global security on the server (S2).