Stream of Knowledge

  Overview of OSPF Definition The Open Shortest Path First (OSPF) protocol, developed by the Internet Engineering Task Force (IETF), is a link-state Interior Gateway Protocol (IGP). At present, OSPF Version 2, defined in RFC 2328, is intended for IPv4, and OSPF Version 3, defined in RFC 2740, is intended for IPv6. Unless otherwise stated, OSPF stated in this document refers to OSPF Version 2. The following describes OSPF fundamentals, and basic OSPF function configuration. Understanding OSPF OSPF Fundamentals Router ID A router requires a router ID if it is to run OSPF. A router ID is a 32-bit unsigned integer, uniquely identifying a router in an AS. A router ID can be manually configured or automatically selected by a router: It is recommended that you manually configure a router ID to ensure OSPF stability. If no router ID is manually configured for a router, the router selects an interface IP address as its router ID. A router selects its router ID based on the following rules: The