Which type of OSPF packet is used by a router to discover neighbor routers?

The type of OSPF packet used by a router to discover neighbor routers is the Hello packet. Hello packets are essential in the OSPF protocol as they help establish and maintain adjacencies between routers. When an OSPF router starts up or when a neighbor goes down, the Hello packets are exchanged to identify and validate neighboring routers on the same network segment.

These packets contain information such as the router’s OSPF priority, Dead Interval, and Router ID, which are crucial for the OSPF process to determine if a neighboring router is reachable and to form an adjacency. The periodic sending of Hello packets allows routers to monitor the status of their neighbors and keep the network topology updated.

In contrast, Link State Update packets are used for sending updates about the state of links and routing information, while Link State Advertisement provides information about the state of a router’s interfaces. Goodbye packets signify the termination of OSPF adjacencies and do not facilitate neighbor discovery. Thus, the Hello packet is specifically designed for establishing and maintaining OSPF neighbor relationships.