Hi,
If you need Layer-3 connectivity only then you can do IPSec VPN.
IPSec VPN can also do secure connections between Edge and non-NSX components (e.g. physical router/firewall)
But if you need Layer-2 connectivity of the networks behind Edge to be extended to the other DC on same Layer-2 network then it will be L2VPN
Bayu Wibowo | VCIX6-DCV/NV
Author of VMware NSX Cookbook http://bit.ly/NSXCookbook
https://github.com/bayupw/PowerNSX-Scripts
https://nz.linkedin.com/in/bayupw | twitter @bayupw