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Beginner

Is the LSA type 1 is sent only to DR and BDR?

Is the LSA type 1 is sent only to DR and BDR?

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Beginner

LSA 1 router LSA being generated by all routers in area

in those area we have DR/BDR for reducing full mesh connectivity by choosing DR/BDR

as a Type 2 LSA

we can remove existing of this By changing Network type point-to-[p-m][nb]

then we have not DR/BDR

but as Characteristic of Link State Protocol (full visibility) here shown as Database you can see all types and also detect which one elected as DR or BDR (or manually with changing cost under ospf process which elected as which role)

in other case which does not exist DR/BDR we have full mesh then Yes to all

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VIP Expert

LSA Type 1 is router LSA, Routers with in the area will flood the Type 1 LSA ( router LSA(, in this LSA you can find who are the neighbours directly connected.

 

this LSA can not go beyond the area of the OSPF.



BB


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Cisco Employee

Hi,

I see you've mentioned DR and BDR so I'm further moving with assumption we're talking about Broadcast or NBMA network.

Answer to your question will be "Yes" and "No", interesting and simple!

There are basically two simple OSPF rules we need to keep in mind for LSA flooding:

1. LSAs need to reach all router. Database of all routers in an area should be same.

2. No looping of LSAs.

 

From the above two points ,we come to understanding that any LSA including Type 1 LSA within the area should be received by everyone! 

This is achieved byDROthers sending their Type 1 LSA only to DR and BDR on 224.0.0.6. DR then replicates and floods the type 1 LSA further to all the DROthers on 224.0.0.5 .

So, Yes, while Type 1 LSAs are sent only to DR/BDR by DROthers , Type 1 LSAs are not sent only to DR/BDR but are further sent down to DROthers by DR.

 

This simple mechanism achieves both the before mentioned rules and also reduces the number of times type 1 LSA is needed to be flooded in a mesh type broadcast topology.

 

Hope this helped!

Cheers

Ashish

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VIP Mentor

Hello

Yes - it will send it to both the DR/BDR then the DR will send an acknowledgment back to the router that originated the lsa and then flood that lsa to all routers including the BDR.



kind regards
Paul

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