From: Jian Gu (guxiaojian@gmail.com)
Date: Thu Jun 01 2006 - 14:25:42 ART
DR does not preempt.
On 6/1/06, 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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This archive was generated by hypermail 2.1.4 : Sat Jul 01 2006 - 07:57:31 ART