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Why is there two DR and two BDR in one area ?

Hey, I’d like to understand how 2 DR occurs here ? What’s affected on this ?

 

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Re: Why is there two DR and two BDR in one area ?

DR/BDR election happens per network segment (broadcast domain) not per Area. So for every Layer 3 point-to-point link (p-to-p) you’ll see that an election has taken place. You can avoid this election configuring both ends of the p-to-p connection with “ip ospf network point-to-point” under interface configuration mode. With the command in place there is no DR/BDR election and therefore no OSPF LSA type 2 network are generated. “Broadcast” network mode is the default which should be used only when there are 3 or more OSPF peers in the network segment (usually a VLAN)

I hope this helps.

Enthusiast

Re: Why is there two DR and two BDR in one area ?


You will not have 2 DRs on same network segment ! one will be DR and other one BDR or non-DR , aka DROTHER. or u will have no DRs no BDRs.
OSPF elects DR per network segment, meaning on each of its own interfaces router has , it does elections. This also depends on type of OSPF network it has: b-cast, non-B-cast, p2p, etc.
R2 has 4 interfaces and might do 4 elections depending on type of OSPF network. by default, Ethernet are B-cast and must have elections before route exchange. Even p2p Ethernet will do elections despite the fact that it does not need to.
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