OSPF lsdb

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Oct 14th, 2008
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Hi all, once routers have established a 2 way state and exchange LSA's (link state database) where does it get all the information for the link state database from ? does this come from the router knowing about all neighbours in the area? does the neighbours advertise the interfaces attached in the Hellos ?

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francisco_1 Wed, 10/15/2008 - 01:54
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once didirectional adj is form, OSPF must exchange and synch the LSDB (state of the links between routers) between the routers by exchanging LSA advertisement between routers. the routers take a copy of the LSA, updates its link-state database (LSDB) and fowards the LSA to all neighboring devices (with the area). In a broadcast network the DR/BDR takes care of the LSA advertisement between the routers.

Carl, the reason why people dont want to help is because of your poor rating. dude, you need to make the effort and rate others for their time/effort spent helping you.


carl_townshend Wed, 10/15/2008 - 04:17
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hi there

so initially are lsa's flooded everywhere on a broadcast network at startup of te ospf process on a router?

francisco_1 Wed, 10/15/2008 - 04:25
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normally having the DR/BDR, LSA's are sent to the DR instead of all routers to prevent flooding.

carl_townshend Wed, 10/15/2008 - 08:12
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So are these LSA's sent once routers have become neighbours? and on a broadcast domain are individual router LSA's sent to the DR/BDR from all DRothers, and then from the DR/BDR to all the DRothers ?

francisco_1 Wed, 10/15/2008 - 10:55
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extactly. remember that the BDR dont interact with the drothers. only the DR interact with the drothers. Once the DR is down, the BDR takes over.



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