DPTIPS: Getting DP GRE to work with VMware 6 and vCenter Server Appliance
http://community.hpe.com/t5/Technical-Support-Services/DPTIPS-Getting-DP-GRE-to-work-with-VMware-6-and-vCenter-Server/ba-p/6838870
If you are trying to configure DP's VMware GRE with a vCenter 6 Server Appliance, this information will be immensely helpful.