You can download Sun Java System Directory Server Enterprise Edition 6.3 software from the following location.
http://www.sun.com/software/products/directory_srvr_ee/get.jsp
The download page serves as a starting point to direct you to the proper downloads depending on the distribution type you need to download. Directory Server Enterprise Edition 6.3 is available in the following distributions.
Native package distribution
Zip distribution
Identity Synchronization for Windows is not delivered in the Directory Server Enterprise Edition native package distribution.
Directory Server Enterprise Edition 6.3 is available in the following forms.
Native patch – patches to upgrade Directory Server Enterprise Edition 6.0, 6.1 and 6.2 native packages installed using the Java ES installer.
Zip based distribution – standalone delivery to install Directory Server Enterprise Edition 6.3 or upgrade Directory Server Enterprise Edition 6.0 and 6.1 and 6.2 zip installations.
The patch release for native installations of Directory Server Enterprise Edition 6.3 on the Microsoft Windows platform is now available. You can download the Directory Server Enterprise Edition 6.3 patch for Windows and upgrade your Directory Server Enterprise Edition installation.
To apply the Directory Server Enterprise Edition 6.3 patch on the native installations on Windows, the minimum required Windows installer version is 3.1.
For information on patch numbers, see Software Installation in Sun Java System Directory Server Enterprise Edition 6.3 Installation Guide.
For the detailed information on what you need to install based on your current installation, refer to the Installation Procedure Quick Reference in Sun Java System Directory Server Enterprise Edition 6.3 Installation Guide.