Can a Subnet Live on Both Sides of an IPSEC Tunnel?

[mario11584]

We are planning on moving to a new office space. We need the networks in the new office space and the current office space up and running at the same time during the transition. This has raised the question on how this can even be done. We were wondering if it's possible to create IPSec VPN tunnels between offices on our PA3020s and have the same subnet live on both sides? So, basically the subnet is extended across the VPN tunnel to the remote side. My assumption is no. I've been working with PAs for about 1.5 years now and I've never heard of this but I thought I would ask since I was informed that OpenVPN supports this feature. Another option we have thought of is using MPLS between sites, which should allow us to do this same thing.

[HULK · Accepted solution]

Hello Mario,

Please find below document, it will give you a working example of configuring IPSec VPN between 2 overlapping networks.

Configuring route based IPSec with overlapping networks

Thanks

[mario11584]

That's awesome! Thanks for that! Genius idea!!

So it basically looks like you "trick", for the lack of a better word, the firewalls into thinking the remote networks are different subnets by using NAT?

Also, is a static NAT and route needed for every single device that lives on opposite sides of the VPN? Or would a dynamic NAT work?

[HULK]

Yes Sir. You are absolutely correct.

Thanks