This is a great setting and very useful, which I hope all users are aware of.
We make use of internal vAPP network on each vAPP which is then connected to the Org DC network. This means that each VM has a NAT’d address to its owned assigned ORG VDC IP.
On the OrgVDC IP we then again use NAT’s to our external networks.
The destination IP for these NATs in the Edge gateway is the Org VDC IP address assigned to the VM.
This means that we need to keep the Org DC ip address always the same for the associated VM within the vAPP.
Why use it:
Whenever you shut down a vAPP and you don’t have this setting enabled, the vAPP will release the Org DC ip address and will get a new address. NOT good!
Now the NAT on the edge gateway is out of the sync with the Org DC IP address for the NAT’d VM, and you will run into problem.