OPSF (Open Shortest Path First) is an advanced routing protocol used to determine where to route packets in a IGP (Interior Gateway Protocol) network. This type of routing protocol is considered to be a link-state protocol.

So what makes the OSPF (Open Shortest Path First) different from most of the other interior gateway protocols you’ll encounter on your CCNA exam? For starters it is the only true link-state routing protocol.

Inside the OSPF Hello Packet OSPF routers create neighbor relationships with directly connected routers by exchanging hello messages. OSPF Router exchange hellos addressed to the ALLSPFROUTERS multicast destination address of 224.0.0.5. OSPF sends out hello packets every 10 seconds with a hold time of 40secs on a broadcast link or Point-to-point link.

Open Shortest Path First (OSPF) is a popular link-state routing protocol for IP networks. OSPF (Open Shortest Path First), which, as the name implies, is an open standard routing protocol used to seek out shortest path routes just like RIP versions. Mind you, the similarities end there!