Can somebody help me in finding the answer to this:
When to use GRE with IPSec?
When to use GIF with IPSec?

http://en.wikipedia.org/wiki/GRE
Try to be clear about what you are talking about.

eg:
http://filext.com/file-extension/GRE
*.gre files seem to be Webalizer.01 language files

For GRE = Graphic Rendering Engine - this is only relevant to MS Windows.

Legacy GIF is almost entirely supplanted by the (arguably superior) PNG format. The only thing left to GIF is simple animations.

So the answer appears to be: use GIF for small animations, use GRE... never.

OK - enough ribbing

In the context of IPSec ...
GRE = Generic Routing Encapsulation.
GIF = Generic tunnel InterFace

http://en.wikipedia.org/wiki/Generic..._Encapsulation
... provides example use of GRE

There is no clear best practice, and IPSec has it's own tunneling mode. You must consider the relative merits of each with respect to your needs and impliment the one that is easiest for you to support and document.

This was my question....
When should anyone use GRE and when GIF....nobody knows....

And you received your reply.
"It depends."

The question is not as simple as it seems. You are talking about protocols which mostly achieve the same end but in slightly different ways. It may be possible to come up with, say, a tabele of tasks which one protocol is more suited for than another... that would make a very looong reply. If I'm going to write that much, I want to get paid for it thank you.

Put it this way - you use the simplest protocol for you to administer for the task in hand. Usually, this would mean GIF. But it really depends on the task, and it depends on you. Nobody can answer this question for you.

Personally, I wouldn't use either.

However, I suspect there is more to this than just the question. If I had some context, I may be able to be more definitive.