DMVPN over IPsec

Hello Azm

For this question, Cisco has an excellent example and explanation as to the order of operations for the scenario you describe. This information can be found here.

Actually, if the IPSec goes down, the GRE tunnel line protocol state will remain down until the IPsec session is fully established. This desired behaviour was established as a result of a Cisco bug with ID CSCum34057 and was included in Cisco IOS Software Releases 15.4(3)M and 15.4(3)S and later. More information about this can be found here.

This will not be able to function. The IP addresses on the tunnel interfaces on both ends of the tunnel must be in the same subnet, just like any other type of connected layer 3 interfaces.

I hope this has been helpful!

Laz