11-27-2017 04:59 PM - edited 11-27-2017 05:10 PM
GRE is stateless, so I am not exactly sure what your looking for.
If your looking for something like what cisco does, I am not sure that is possible, that may be a cisco only thing though I never really looked into it).
11-29-2017 03:03 AM
What comes to mind:
LB group using single interface: either use GRE tunnel inside or outside interface. As LB test use ping towards corresponding remote interface. Use transition script to do whatever you want on up/down event