Get My Palo Alto Networks Firewall Course here: Get 30% off with: You can use promo code: OSCAROGANDO2 Follow Me on Twitter: Open Shortest Path First (OSPF) is a routing protocol for Internet Protocol (IP) networks. It uses a link state routing (LSR) algorithm and falls into the group of interior gateway protocols (IGPs), operating within a single autonomous system (AS). It is defined as OSPF Version 2 in RFC 2328 (1998) for IPv4.