OSPF states

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Nov 22nd, 2007
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I am not clear on OSPF. Why do we need two kinds of states in OSPF ie OSPF neighbor states and interface states? I know abt neighbor states, but what is the significance of interface states?

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royalblues Thu, 11/22/2007 - 03:01
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The Neighbor state machine as you know tracks the state of the neighbor i.e down, init, exstart, full etc.

The interface state machine on the other hand tracks the state of the interface i.e whether it is down, P2P, waiting, DR, BDR or loopback



bvsnarayana03 Thu, 11/22/2007 - 03:11
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OSPF is a link state protocol, which means it has a lot to do with the link or the state of the link. Link can be considered a synonym for interface, when referring to ospf.So, it is the interface state that determines how an ospf router negotiates with neighbor.

When an ospf router sends HELLO pkts to its neighbor for negotiation, it contains info obtained in the interface state to tell the neighbor about its own state.

So to conclude, interface state determines the router's own state to neighbors. while neighbor state is as the name indicates.

hope this clarifies. you may revert for further clarity.

pls rate if helped.

balajee Thu, 11/22/2007 - 05:38
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Thanks for the good explaination. I got the answer from ur explaination


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