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List:       ms-ospf
Subject:    Re: Receiving Self Originated Network LSA
From:       Sina Mirtorabi <sina () CISCO ! COM>
Date:       2004-10-08 6:00:26
Message-ID: 165d01c4acfc$1d721b90$6001a8c0 () amer ! cisco ! com
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Mukesh,

->
->Hi Mukesh,
->If I understand your question, R2 should do #2 as long
->as R1 and R2 are in a state >= EXCHANGE on interface a.
->If R1 and R2 area in a state < EXCHANGE on interface a
->R2 will drop the LS Update.
->
->Hope this helps,
->Acee
->----- Original Message -----
->From: <Mukesh.Gupta@NOKIA.COM>
->To: <OSPF@PEACH.EASE.LSOFT.COM>
->Sent: Thursday, October 07, 2004 8:05 PM
->Subject: Receiving Self Originated Network LSA
->
->
->Hi All,
->
->Consider this topology..
->           b
->() -- R1 ===== R2 -- ()
->           a
->
->Where R1 and R2 are connected by 2 interfaces a and b
->and running OSPF on both of them.  () is network with
->more routers.  Let say everything is in area backbone.
->R1 is DR for network a and R2 is DR for network b.
->
->Now R2 crashes and comes back up.  It establishes
->adjacency with R1 and generates a network LSA for
->network b with sequence number 1.

As a side note, R2 can generate network LSA if it is DR however in
normal circumstances, R1 will do a NeighborChange event (because R2 adj
goes to Init or lower) and R1 elect itself as DR. Therefore R2 cannot
become DR when it comes back up...


Sina


->Now let say R2
->receives a self originated network LSA for network b
->with sequence number 7 on interface a.  What should
->it do ?
->
->1) silently drop the packet because the packet was
->   received on the wrong interface ?  The LSA will
->   be flushed or reoriginated when the same LSA will
->   be received on network b.
->
->2) or look up the interface that has the ip address
->   mentioned in the ls id of the LSA and reoriginate
->   the LSA if it is DR on that interface or flush the
->   LSA if it is not.
->
->Regards
->Mukesh
->
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