Dictionary · Protocols and Ports
OSPF
OSPF — Open Shortest Path First
Routing · Advanced
An interior link-state routing protocol. Routers share the state of their links and each builds a map of the area. It is IP protocol 89, not a TCP or UDP port.
Inside one organization, routers use it to learn the whole area and calculate paths. It reacts to changes without waiting for information to hop slowly from router to router.
Example: All routers in an area learn that a link failed and compute new shortest paths from the updated map.
Common misconception
- It does not use a TCP or UDP port. It is carried directly as Internet Protocol number 89.