Reasons for OSPF Neighbor Failure

B.

OSPF (Open Shortest Path First) is a routing protocol that uses link-state technology and is widely used in large networks. In order for OSPF to function correctly, devices need to establish OSPF neighbor relationships, which enable them to exchange link-state advertisements (LSAs) and build their topology databases.

There are several reasons why two devices may fail to establish an OSPF neighbor relationship, but the most common ones are related to the configuration of the OSPF parameters:

A. The two devices have different process IDs: OSPF process IDs are locally significant and are used to differentiate between multiple instances of OSPF running on the same device. If two devices have different process IDs, they will not be able to establish an OSPF neighbor relationship. To fix this issue, the process IDs must be the same on both devices.

B. The two devices have different network types: OSPF supports several network types, including point-to-point, broadcast, non-broadcast, and point-to-multipoint. If two devices are configured with different network types on the same segment, they will not be able to establish an OSPF neighbor relationship. To fix this issue, the network types must be the same on both devices.

C. The two devices have different router IDs: OSPF router IDs are used to identify each device in the OSPF domain. If two devices have different router IDs, they will not be able to establish an OSPF neighbor relationship. To fix this issue, the router IDs must be the same on both devices.

D. The two devices have the same area ID: OSPF uses area IDs to group together networks and devices that have the same topology. If two devices are in the same area and have the same area ID, they will not be able to establish an OSPF neighbor relationship. To fix this issue, the area IDs must be different on both devices.

In summary, to establish an OSPF neighbor relationship between two devices, the devices must have the same OSPF process ID, network type, and router ID, and they must be in different OSPF areas if they have the same area ID.