Fortinet FortiGate 1U Quick Start Manual page 201

Configuring the HQ's IPsec
VPN
On the HQ FortiGate, go to VPN > IPsec >
Auto Key (IKE).
Select Create Phase 1. Set IP Address
to the IP of the Branch FortiGate, Local
Interface to the Internet-facing interface,
and enter a Pre-shared Key.
Using IPsec VPN to provide communication between offices 181