Ok, so I'm asking a more specific question this time. I'm writing a paper about Cisco's DMVPN and one of the tasks I have is to make the analysis of available network solutions which use dynamic VPN tunnels. Because the paper is about DMVPN, I have to compare those solutions to it. I know there are a lot of dynamic tunneling technologies but I'm looking for ones that can be compared to DMVPN. So the question is: are there any technologies which use dynamic VPN tunnels (not necessarily using crypto) that can be compared to DMVPN? What are those technologies?