VPN Site-to-Site bitween Fortigate and Cisco ASA (with virtual ip from external subnets)

[RuselB]

Good day! Please help with setting up a VPN Site-to-Site on Fortigate. We are considering replacing the Cisco ASA 5520 with a Fortigate 100E (200E). On the test bench, it is not possible to configure a VPN Site-to-Site between Fortigate and Cisco ASA (using the virtual IP from the external subnet). Although this scheme works on a real VPN Site-to-Site hardware between the Cisco ASA 5520 and 5505, but it is not possible to achieve the same result on Fortigate.