What is the purpose of the hello packet in OSPF?

The purpose of the hello packet in OSPF is to establish and maintain adjacencies between OSPF routers. When OSPF routers want to form a neighbor relationship, they exchange hello packets. This interaction allows routers to discover each other on the same local network segment.

Hello packets include essential information such as the router IDs, the OSPF area ID, and the hello and dead intervals. By exchanging these packets, routers can verify that both sides are active and can communicate effectively. Additionally, the hello packet helps determine whether routers can remain adjacent based on the parameters they negotiate, which is crucial for OSPF's operation.

Maintaining these adjacencies is vital for the stability and efficiency of OSPF, as it directly affects the ability to form the link-state database, which is essential for OSPF to function correctly. Thus, the correct answer highlights the foundational role hello packets play in ensuring a robust OSPF network topology.