Site-to-Site VPN IPSec - Routing with identical Remote Networks

Question

Hello Guys, 
 here is a quick and dirty illustration of the current setup: 
 
 The hosts sit all in de same internal subnet 192.168.150.0/24 and the remote offices all have there unique subnets. Till now. 
 A new customer have the same Subnet as an already existing one, so is this even possible? 
 When i look into the routingtable, i just can see that the Remote Subnets are routed "into" the ipsec tunnels. 
 192.168.0.0/24 dev eth0 proto ipsec scope link 
192.168.2.0/24 dev eth0 proto ipsec scope link 
192.168.10.0/24 dev eth0 proto ipsec scope link 
192.168.100.0/24 dev eth0 proto ipsec scope link 
 
 Its all live and productive, so i dont have the posibility to do a lot of Trial&Error. 
 
 thanks

BAlfson · Answer

Hi, Robert, and welcome to the UTM Community! 
 It's unfortunate that any organization uses subnets in the 192.168.0.0/16 range - those should only be used for homes and public hotspots. ISPs and very large organizations should use subnets in 10.0.0.0/8. All other organizations should use subnets in 172.16.0.0/12. 
 You will want to use a subnet in 172.16.0.0/12 for both sides of the tunnel when applying the techniques described in How to tunnel between two UTMs which use the same LAN network range & More VPN between same subnets . 
 Cheers - Bob