Re: OSPF and Priorities

From: Paul Cosgrove (paul.cosgrove@heanet.ie)
Date: Tue Sep 09 2008 - 11:23:46 ART

Hi Andy,

Just wondering if anyone has been able to verify the operation of this
command as described in the book?

The errata list for the command and config book can be seen at:
http://www.ciscopress.com/bookstore/product.asp?isbn=1587050714#info3
It includes the following, but I don't have the book myself, so perhaps
someone else can clarify whether or not this is about the same section:
""
Page 289  The second sentence under the Purpose heading should read,
The router with the highest
                   non-zero priority will be elected the DR.
""

Paul.

andy wrote:
> I did a little looking and it seems that:
>
> From "CiscoR OSPF Command and Configuration Handbook (CCIE Professional
> Development)"
>
> Neighbor ospf priority lowest wins (section 11-5)
>
> Interface ospf priority highest wins (section 19-8)
>
> This was news to me. I always thought highest won.
>
> Andy
>
> -----Original Message-----
> From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf Of
> Jonathan Greenwood II
> Sent: Sunday, September 07, 2008 9:56 PM
> To: Alan Ewer
> Cc: Cisco certification
> Subject: Re: OSPF and Priorities
>
> How is it that i cannot get this command to set the DR
> (ie the priority) from a neighbour.. ?
>
>
> Hmm I just labbed it up. When I initially clear the proccess on R1 it shows
> the priority information being exchanged
>
> Neighbor ID Pri State Dead Time Address Interface
> N/A 100 ATTEMPT/DROTHER 00:01:53 1.1.1.2
> FastEthernet00
>
> But once the state is has established it shows as Priority 1
>
> Neighbor ID Pri State Dead Time Address Interface
> 150.20.2.2 1 FULL/DR 00:01:59 1.1.1.2
> FastEthernet00
>
> Good question though I have to play with it a little more or read something
> about it more. I agree with you on: R2's default priority of 1 should be
> over-ruled by the "suggested priority
> of 100
>
> Jonathan
>
>
>
>
> On Sun, Sep 7, 2008 at 6:17 PM, Alan Ewer <acewer64@gmail.com> wrote:
>
>> Hi All this is a bit of a picky question...here goes..
>> OSPF will use the DR with the highest priority right..
>> this can be set on an interface using the "ip ospf priority 100" command
>> ...all good...no problem
>>
>> however the command neighbor 1.2.3.4 priority 100 is to set a neighbours
>> priority to 100 (if it has a lesser priority set..)
>> The neighbor assesses the priority in the incoming hello and the
> configured
>> and the highest priority wins ...Am I right so far..
>>
>> How is it that i cannot get this command to set the DR
>> (ie the priority) from a neighbour.. ?
>>
>> Ie if R1 and R2 are configured as NBMA.
>> R1 is 1.1.1.1 and R2 is 1.1.1.2
>>
>> I want R2 to be the DR but am not permitted to set a priority. I should be
>> able to set R1 up as follows:
>> ==================
>> router ospf 1
>> nei 1.1.1.2 priority 100
>> ====================
>> R2's default priority of 1 should be over-ruled by the "suggested priority
>> of 100
>>
>> What am I missing here ??
>>
>> Regds
>> Alan E
>> Australia
>>
>>
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>>
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