1.) DLP Agents are simply one major version backwards compatible. So DLP 14 would be compatible with agents 12.0 & 12.5 but NOT with 11.x (11.5 and 11.6 ).
2.) DLP only supports one major release upgrade. For your 11.6.3 system that would mean you could follow the below upgrade plan:
(a.) Patch Oracle to 11.2.0.3 & upgrade DLP Enforce + Detection Servers from 11.6.3 --> 12.0
(b.) Patch Oracle to 11.0.2.4 & upgrade DLP Enforce + Detection Servers from -> 12.0 -> 14.0
(c.) Upgrade DLP Enforce + Detection Servers from -> 14.0 -> 14.0.1
To summarize:
DLP - Go to 12.x & later to 14.x for Enforce & Detection servers. Patch Oracle at each upgrade. Gradually upgrade your clients. Clients are ONE VERSION backwards compatible.
For Enforce upgrade I prefer the manual upgrade which is quite solid with chances of failure, you simply run the upgrade binary after unzipping:
https://www-secure.symantec.com/connect/articles/u...
For Detection server, normally the push upgrade from enforce fails. I would keep a winrar or 7zip handy here as well and follow the same article above. This time unzip the windowsdetectionupgradepackage.jar in the \SymantecDLP\Protect\updates directory and follow instructions on Page # 29 on the upgrade guide below:
http://clientui-kb.symantec.com/resources/sites/BU...
I merely tried to outline the process. Do cover the pre-requisites like DB / file / policy backup etc. before proceeding :-)
Hope this helps!!!