Tunnel IP Address

[MrBeginner]

Dear All,

I am beginner and i would like to ask stupid questions.

i would like to know Tunnel IP address can i assign /32  for VTI ,DMVPN,IPSec ?

In the lab i can assign. i would like to know what is the best practice ?

[Mohammed al Baqari]

If you are planning to route traffic over the tunnel then it has to allow
more IPs because the next hop of the routes has to be in the same subject
of the tunnel

[Rob Ingram · Accepted solution]

Hi,
When using a VTI (FlexVPN for example) you do also have the option to configure the tunnel interface with the command "ip unnumbered <interface>", the IP address of this interface does not need to be in the same subnet as the peer router, they can be in unique. You can still use a dynamic routing protocol and form an adjacency.

I have found this to be quite common in FlexVPN deployments and Cisco documentation examples usually use the "ip unnumbered" command also.

E.g:-
interface loopback0
ip address 10.5.0.1 255.255.255.255

interface tunnel0
ip unnumbered loopback0

HTH