Chapter 2 Advanced Routing for FortiOS 5.0 : Open Shortest Path First (OSPF) : OSPF Background and concepts : The parts and terminology of OSPF
  
The parts and terminology of OSPF
Parts and terminology of OSPF includes:
• OSPFv3 and IPv6
• Router ID
• Adjacency
• Designated router (DR) and backup router (BDR)
• Area
• Authentication
• Hello and dead intervals