Which OSPF state indicates that the router has finished transmitting its database but is still receiving database information?
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A. B. C. D.A
In the loading state, routers send link-state request packets. During the adjacency, if a router receives an outdated or missing link-state advertisement (LSA), it requests that LSA by sending a link-state request packet.
Note: OSPF states for adjacency formation are Down, Init, Attempt, 2-way, Exstart, Exchange, Loading and Full.
Incorrect Answers:
B: After two OSPF neighboring routers establish bi-directional communication and complete DR/BDR election (on multi-access networks), the routers transition to the exstart state. In this state, the neighboring routers establish a master/slave relationship and determine the initial database descriptor (DBD) sequence number to use while exchanging DBD packets.
C: The 2-way state indicates that the router has seen its own Router ID in the Neighbor field of the neighbor's HELLO packet. Receiving a Database Descriptor
(DBD) packet from a neighbor in the init state will also a cause a transition to 2-way state.
D: Once the master/slave relationship has been negotiated (the router with the highest Router-ID becomes the master), the neighboring routers transition into the exchange state. In this state, the routers exchange DBD packets, which describe their entire link-state database. The routers also send link-state request packets, which request more recent link-state advertisements (LSA) from neighbors.
http://www.cisco.com/c/en/us/support/docs/ip/open-shortest-path-first-ospf/13699-29.html#anc10The OSPF (Open Shortest Path First) protocol uses several states to establish neighbor relationships and synchronize link-state databases between neighboring routers. The correct answer to the question is option D: Exchange.
Here's a brief explanation of each OSPF neighbor state:
Down: In this state, there is no communication between two routers.
Init: In this state, a Hello packet has been sent by one router, and the other router has responded with a Hello packet.
2-Way: In this state, the routers have exchanged their router ID information and agree on parameters such as the network type and subnet mask. However, they have not yet established a master-slave relationship.
Exstart: In this state, one router becomes the master and the other becomes the slave. The master sends a database description (DBD) packet to the slave, which responds with an acknowledgement (ACK) packet.
Exchange: In this state, the routers exchange link-state advertisements (LSAs) in the form of DBD packets. The router in this state has finished transmitting its database, but it is still receiving DBD packets from its neighbor.
Loading: In this state, the routers exchange LSAs that were missing from their databases during the Exchange state. The router in this state is waiting for all the necessary LSAs before moving to the next state.
Full: In this state, the routers have completed the exchange of LSAs, and their link-state databases are synchronized. They can now forward packets based on the shortest path to the destination.
In summary, the Exchange state indicates that the router has finished transmitting its database but is still receiving database information from its neighbor.