elect DR

Unanswered Question
Aug 9th, 2009
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Hi,


I have one question. there are two routers (R1 and R2)


! R1

router ID: 200.115.20.149

FE0/0: 192.168.30.10/24



! R2

router ID: 210.113.194.11

FE 0/0: 192.168.30.11/24

priority: 1



After the election, R1 becomes the DR, R2 is BDR. why?


rdgs


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Edison Ortiz Sun, 08/09/2009 - 08:16
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Whatever router boots up first, becomes the DR. If R1 had OSPF up and running before R2, it will be the DR as there isn't any preemption under OSPF. You would have to clear ospf process on both routers at the same time so R2 can regain DR status.


HTH,


__


Edison.

anitachoi3 Sun, 08/09/2009 - 08:31
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Hi,


What is the election priority of DR and BDR?


rdgs


Edison Ortiz Sun, 08/09/2009 - 10:41
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When the router boots up and OSPF is activated on an interface, it queries all OSPF speaking devices in a LAN for DR/BDR status. If none exists, it assume the DR role. A second router boots up on that same LAN and do the same, will find the current DR running on that segment and will assume the BDR role regardless of its OSPF priority and|or RouterID.


There is no preemption under OSPF, in other words, the second router won't take over the first router's assignment.


For that reason, if you want to ensure a router will always be the DR of a segment, you must change the OSPF priority on this router to 255 and all other routers to 0 so they won't participate on the election - regardless when they were booted up.


HTH,


__


Edison.

suryakant.chavan Sun, 08/09/2009 - 10:42
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Both DR & BDR has same priority that is 1


You can see this under

show ip ospf neigbhor

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