From: Alan Ewer (acewer64@gmail.com)
Date: Wed Sep 10 2008 - 02:44:54 ART
Hi Guys..
Yes thinking about this... I guess the best way i have found to think of
this is as follows:
1. router is configured with the "neighbor x.x.x.x priority 1 to demote
neighbours from becoming the DR..
2. then the lowest priority (between "suggested" value and interface
configured value .becomes the "actual" priority
3. then from that priority a comparison of who has the highest priority wins
and becomes the DR
thats how I now understand it to work...will verify on my lab a bit later
on..
Thanks for the input though guys... very helpful !!
Regds
Alan - Brisbane - Australia
On 9/10/08, Paul Cosgrove <paul.cosgrove@heanet.ie> wrote:
>
> 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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