Juniper Networks Certified Internet Specialist Exam JN0-360: Understanding OSPF Neighbor States

Understanding OSPF Neighbor States

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Question

You have two OSPF routers that are trying to form an adjacency. When you issue the command show ospf neighbor, you see that one router is in the loading state and the other is in the full state. Why are you seeing the router's state as loading?

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Explanations

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A. B. C. D.

B

In OSPF, routers form adjacencies with their neighbors in order to exchange routing information. During this process, there are several states that a router goes through before reaching the full state, where the adjacency is considered stable and all routing information has been exchanged.

When a router is in the loading state, it means that it has received a database description (DBD) packet from its neighbor, but has not yet received all of the link-state advertisement (LSA) information that it needs. There are a few reasons why this might be the case:

A. The router does not know about the received LSA header and has transmitted a link-state request. This means that the router has received a DBD packet from its neighbor, but has not yet received all of the LSAs that it needs. It has therefore sent a link-state request (LSR) message to its neighbor requesting the missing LSAs. Once it receives the requested LSAs, it will move to the next state in the adjacency process.

B. The router has finished transmitting, but is still receiving database information. In this case, the router has sent its own DBD packet to its neighbor and is waiting to receive the LSAs that it needs to complete the adjacency. It may also be receiving other DBD packets from its neighbor that contain additional LSAs.

C. The router is waiting for a start event. This means that the router is waiting for some event to occur before it can move to the next state in the adjacency process. This might be a timer expiring, a neighbor coming back online, or some other event that triggers the adjacency process to continue.

D. The router has established bidirectional communication with its peer. This means that the router has completed the initial steps of the adjacency process and has established bidirectional communication with its neighbor. However, it still needs to receive and process LSAs before the adjacency can be considered complete.

In summary, when a router is in the loading state in OSPF, it means that it has received a DBD packet from its neighbor but has not yet received all of the LSAs that it needs to complete the adjacency. This can happen for a variety of reasons, including missing LSAs, waiting for a start event, or simply still receiving database information.