Chapter 16 SSL VPN for FortiOS 5.0 : Basic Configuration : Configuring security policies : Enabling a connection to an IPsec VPN
  
Enabling a connection to an IPsec VPN
You might want to provide your SSL VPN clients access to another network, such as a branch office, that is connected by an IPsec VPN. To do this, you need only to add the appropriate security policy. For information about route-based and policy-based IPsec VPNs, see the IPsec VPN Guide.
See Also
Route-based connection
Policy-based connection
Firewall addresses
Create an SSL VPN security policy
Create a tunnel mode security policy
Split tunnel Internet browsing policy