From: Ivan (ivan@iip.net)
Date: Fri Jun 02 2006 - 07:01:27 ART
As i understand Rack1R6 have only 1 interface in OSPF (S0.204).
After only interface is down OSPF proccess have no interface within.
-------------------------------
*Mar 1 03:42:51.511: %OSPF-5-ADJCHG: Process 1, Nbr 150.1.4.4 on Serial0.204
from FULL to DOWN, Neighbor Down: Interface down or detached
-------------------------------
Therefore neither DR nor BDR have elected.
To correct situation you need interface S0.204 up.
> Bob,
>
> >If I shut the R6 interface F0/0, then R2 transistions to DR. When R6
> > comes
>
> back up it becomes BDR, and stays that way.
>
>
> Did you get that result from your lapping it?
>
> This is what my lab results is telling me after various poking around...
>
> 1. When R6 is OSPF enabled, it send hello out and wait, after awhile, if
> there is no reply, it elect itself as the DR.
> 2. When R2 is OSPF enabled even with a higher priority/RID, it becomes the
> BDR.
> 3. When I shutdown R6 interface, R2 never become the DR or the BDR, my
> debug shows <DR=0.0.0.0; BDR=0.0.0.0> on R2.
> 4. When I shutdown R2 interface instead, R6 loses it DR capabilities which
> it use to possess even before OSPF was enabled on R2.
> 5. Clear ip ospf process does not yield a consistent result, even when done
> on both routers.
>
> My coffee have started kicking in and it appears that I need a refill.
>
> Thanks.
> Godswill Oletu
>
> ----- Original Message -----
> From: Bob Sinclair
> To: Godswill Oletu ; Jian Gu
> Cc: Cisco certification
> Sent: Thursday, June 01, 2006 3:25 PM
> Subject: Re: DR Election: Incase of a Priority Tie, Highest RID Wins -
> Truth or Fallacy?
>
>
> Godswill,
>
> My results differ using two routers running (C3640-JK9O3S-M), Version
> 12.4(5). R2 with RID 172.16.102.1 is connected to R6 with RID 172.16.106.1
> over FastEthernet. Otherwise all is default.
>
> Normally, R6 is the DR and R2 is the BDR, based on R6 having the higher
> RID.
>
> If I shut the R6 interface F0/0, then R2 transistions to DR. When R6
> comes back up it becomes BDR, and stays that way.
>
> At least on this platform, with this IOS, in the month of June, there is
> a DR on a 1-router network and boot sequence does determine DR on a
> 2-router broadcast segment.
>
> Winning the DR election is like winning a door prize: you must be
> present to win. If there is only one router on a broadcast network, it
> will become the DR and a router with a higher RID will not preempt.
>
> HTH,
>
>
>
> Bob Sinclair
> CCIE #10427, CCSI 30427
> www.netmasterclass.net
>
> ----- Original Message -----
> From: Godswill Oletu
> To: Jian Gu
> Cc: Cisco certification
> Sent: Thursday, June 01, 2006 2:34 PM
> Subject: Re: DR Election: Incase of a Priority Tie, Highest RID Wins -
> Truth or Fallacy?
>
>
> Jian,
>
> The concept of preemption does not apply in a two router OSPF segment.
> When
> one router goes down, so does the OSPF ajacency and neigbor
> relationship with
> the other router. The second router cannot transistion from a BDR to a
> DR all
> by itself, neither will it remain a BDR in the absent of the other
> router. So,
> when the old router comes back online, there will be no DR or BDR on
> that segment, the OSPF ajacancy will be renegotiated from the beginning as
> if it
> never occurred before and so will be the election of DR/BDR.
>
> HTH
> Godswill Oletu
> ----- Original Message -----
> From: Jian Gu
> To: Godswill Oletu
> Cc: Cisco certification
> Sent: Thursday, June 01, 2006 1:25 PM
> Subject: Re: DR Election: Incase of a Priority Tie, Highest RID Wins
> - Truth
> or Fallacy?
>
>
> 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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-- Ivan
This archive was generated by hypermail 2.1.4 : Sat Jul 01 2006 - 07:57:31 ART