Chapter 2 Advanced Routing for FortiOS 5.0 : Open Shortest Path First (OSPF) : Basic OSPF example : Configuring other networking devices
  
Configuring other networking devices
The other networking devices required in this configuration are on the two ISP networks, the BGP network for the main Internet connection, and the DSL backup connection.
In both cases, the ISPs need to be notified of the OSPF network settings including router IP addresses, timer settings, and so on. The ISP will use this information to configure its routers that connect to this OSPF network.