Re: OSPF Duplicate Router-id - problem areas

We always hear that the CCIE isn't a best practice test, but I can't
see the proctors/lab writers forcing you to utilize something that is
just as bad of an idea as having hosts with the same router ID.

On Thu, Dec 22, 2011 at 6:18 AM, Paul Cosgrove
<paul.cosgrove.groupstudy_at_gmail.com> wrote:
> Generally people define a loop back as rid, using the same interface for
> device management. Using duplicate rids is taking a risk without any
> benefit. The rid does not need to exist as an ip, so using duplicates
> wouldn't even save addresses. Even if you were to have a topology where
> duplicate rids were not causing problems, they may do so when that network
> is later modified.
> On Dec 22, 2011 5:41 AM, "Tom Kacprzynski" <tom.kac_at_gmail.com> wrote:
>
>> Hello,
>> I have a quick question regarding OSPF Router-id uniqueness. I know that
>> router-id needs to be unique in OSPF. So I did some testing.
>>
>> Looks like in the same area you'll run into problem.
>>
>> I'm thinking that if you have virtual-links, then yeah that would give your
>> problems.
>>
>> You can't have any ABR or ASBR with router-id that are duplicate, that is a
>> problem for sure.
>>
>> In you have member routers in different areas with duplicate router-id,
>> you'll run into problems if one of the routers sharing the same router-id
>> is originating an external route (FLOOD_WAR).
>>
>> But outside of that, everyone else would see the advertising router as ABR
>> and not the router with duplicate router-id so that should be ok.
>>
>> Are there any other scenarios? Seems to me saying that the whole AS needs
>> to have unique router-id might be too general and there are few cases where
>> you won't need that. I'm not saying to start configure them duplicate, but
>> just exploring the concept further.
>>
>>
>> Thank you very much in advance for any input.
>>
>> Tom Kacprzynski
>>
>>
>> Blogs and organic groups at http://www.ccie.net
>>
>> _______________________________________________________________________
>> Subscription information may be found at:
>> http://www.groupstudy.com/list/CCIELab.html
>
>
> Blogs and organic groups at http://www.ccie.net
>
> _______________________________________________________________________
> Subscription information may be found at:
> http://www.groupstudy.com/list/CCIELab.html

Blogs and organic groups at http://www.ccie.net
Received on Thu Dec 22 2011 - 10:06:21 ART