From: WorkerBee (ciscobee@gmail.com)
Date: Thu Jun 01 2006 - 14:36:08 ART
This is not weird. It depends which router boots up first and
get it's ospf process up. Router-ID is not pre-emptive in nature.
If there is already a DR, a more attractive Router-ID router boots
up will not take over the DR role.
If you perform "clear ip ospf process" after both routers have
their peering form, both routers will negotiate "correctly" based
on the Router-ID selection criteria since now both routers
already booted up and no DR/BDR in that segment.
On 6/2/06, Godswill Oletu <oletu@inbox.lv> wrote:
> Hi,
>
> This topic was beaten to death the past few weeks on the group and the general
> concession is that, when there is a tie on the priority vlaues, the highest
> Router-ID wins, Cisco online documentation have various pages confirming this
> as well. But, I do not know if anyone labbed this up and fool-proof this
> concept.
>
> I am have labbed that exact scenario, that required that a particular router
> be elected the DR in segment of two routers, the neighbor or priority commands
> are not to be used.
>
> The results I am getting is not consistent across the board:
>
> Little preview of my configures:
>
> Rack1R2:
> interface Serial0
> no ip address
> encapsulation frame-relay
> no frame-relay inverse-arp
> !
> interface Serial0.204 point-to-point
> ip address 144.1.24.2 255.255.255.0
> ip ospf network broadcast
> frame-relay interface-dlci 204
> !
> router ospf 1
> router-id 222.2.2.2
> log-adjacency-changes
> network 144.1.24.2 0.0.0.0 area 0.0.0.0
> network 150.1.2.2 0.0.0.0 area 0.0.0.0
> !
> -----------------------------------------------------------------------------
> --
> Rack1R4:
> interface Serial0/0
> no ip address
> encapsulation frame-relay
> no frame-relay inverse-arp
> !
> interface Serial0/0.402 point-to-point
> ip address 144.1.24.4 255.255.255.0
> ip ospf network broadcast
> frame-relay interface-dlci 402
> !
> router ospf 1
> router-id 150.1.4.4
> log-adjacency-changes
> network 144.1.24.4 0.0.0.0 area 0.0.0.0
> network 150.1.4.4 0.0.0.0 area 0.0.0.0
> !
> -----------------------------------------------------------------------------
> -------
> Results:
> Rack1R2#clear ip ospf process
> Rack1R2#sho ip ospf nei
> Neighbor ID Pri State Dead Time Address Interface
> 150.1.4.4 1 FULL/DR 00:00:37 144.1.24.4 Serial0.204
> Rack1R2#
>
> Rack1R4#show ip ospf nei
> Neighbor ID Pri State Dead Time Address Interface
> 222.2.2.2 1 FULL/BDR 00:00:32 144.1.24.2
> Serial0/0.402
> Rack1R4#
>
> Despite the fact that Rack1R4 have the lowest Router-ID, it was elected the DR
> for that segment and Rack1R2 who have the highest Router-ID settled for the
> less fancy job of a BDR.
>
> Now............
>
> Rack1R4#clear ip osp nei
> Rack1R4#sho ip ospf nei
> Neighbor ID Pri State Dead Time Address Interface
> 222.2.2.2 1 FULL/DR 00:00:39 144.1.24.2
> Serial0/0.402
> Rack1R4#
>
> Rack1R2#sh ip ospf nei
> Neighbor ID Pri State Dead Time Address Interface
> 150.1.4.4 1 FULL/BDR 00:00:34 144.1.24.4 Serial0.204
> Rack1R2#
>
>
> Now, the roles have been revised, completely negativing the 'supposed'
> influence that a higher Router-ID should have in the DR/BDR election process.
>
> Or, are mine missing something here? Maybe my coffee have not sink in
> yet...but your contribution is highly welcome.
>
> Thanks.
> Godswill Oletu
>
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