OSPF - Open Shortest Path First Flashcards
What do “Hello” packets do and what’s the default interval for it being sent.
Hello packets are used to see if other OSPF routers are listening and vice versa. They’re sent out every 10 seconds by default.
What do DataBase Description (DBD) packets do?
DBD packets are used to share network information to adjacent routers.
What do Link State Request (LSR) packets do?
LSR packets are sent out to request information if any information about the network that is received from the DBD is missing.
What is a dead interval and how long is the default setting?
Dead interval is how long a router waits to get a reply. This defaults to 4x Hello Interval.
What happens when you connect two OSPF routers (router 1 and router 2) and have them exchange information?
Router 1 and router 2 will establish a two-way connection by sending each other a hello packet and sharing its neighbors. Then they move to the exchange state where they send each other a DBD packet and negotiate who starts sharing first. After, they send an LSAck to acknowledge the DBD was received. Then they send the LSR and LSU to update each other in the Loading state. Finally they send an LSAck to confirm they received the information which puts it in the Full state.
