Re: BGP/OSPF router-id mismatch and the BGP synchronization

Not realy. But it can hapen no Gold medals to be awarded

Sent from my BlackBerry. smartphone from Zain Kenya

-----Original Message-----
From: Narbik Kocharians <narbikk_at_gmail.com>
Date: Sat, 13 Feb 2010 10:48:19
To: <bahati_at_6telecoms.co.tz>
Cc: <Keegan.Holley_at_sungard.com>; Jared Scrivener<lists_at_jaredscrivener.com>; Cisco certification<ccielab_at_groupstudy.com>; Divin Mathew John<divinjohn_at_gmail.com>; Marcel Lammerse<m.lammerse_at_mac.com>; <nobody_at_groupstudy.com>
Subject: Re: BGP/OSPF router-id mismatch and the BGP synchronization rule

It's one of those one in million scenarios/situations that use to happen
when Rocky Marciano was the champ.

On Sat, Feb 13, 2010 at 10:03 AM, <bahati_at_6telecoms.co.tz> wrote:

> Depends on the situation at hand
>
>
> Sent from my BlackBerry. smartphone from Zain Kenya
>
> -----Original Message-----
> From: <Keegan.Holley_at_sungard.com>
> Date: Sat, 13 Feb 2010 11:52:44
> To: Jared Scrivener<lists_at_jaredscrivener.com>
> Cc: Cisco certification<ccielab_at_groupstudy.com>; Divin Mathew John<
> divinjohn_at_gmail.com>; Marcel Lammerse<m.lammerse_at_mac.com>; <
> nobody_at_groupstudy.com>
> Subject: Re: BGP/OSPF router-id mismatch and the BGP synchronization
> rule
>
> Seriously though. This feature seems to have no benefit at all.
>
>
>
> From:
> Jared Scrivener <lists_at_jaredscrivener.com>
> To:
> Keegan.Holley_at_sungard.com
> Cc:
> Divin Mathew John <divinjohn_at_gmail.com>, Cisco certification
> <ccielab_at_groupstudy.com>, Marcel Lammerse <m.lammerse_at_mac.com>,
> nobody_at_groupstudy.com
> Date:
> 02/13/2010 08:16 AM
> Subject:
> Re: BGP/OSPF router-id mismatch and the BGP synchronization rule
> Sent by:
> <nobody_at_groupstudy.com>
>
>
>
> Who said the rules of networking had to be consistent? ;)
>
> --
> Cheers,
>
> Jared Scrivener
> CCSI #30878, CCIE3 #16983 (R&S, SP, Security)
> www.MicronicsTraining.com <http://www.micronicstraining.com/>
> Sr. Technical Instructor
>
> YES! We take Cisco Learning Credits!
> Training And Remote Racks available
>
> LinkedIn:www.linkedin.com/in/jaredscrivener
>
>
> On Sat, Feb 13, 2010 at 11:04 PM, <Keegan.Holley_at_sungard.com> wrote:
>
> > Couple this with the fact that I can't even remember the last time I
> came
> > across a router with synchronization turned on and this becomes a nice
> > little gotcha. It's strange that the BGP process doesn't consider a
> route
> > good if it's protocols are using different router ID's. Shouldn't it
> > simply "trust" the IGP to make the right decision? Matching router ID's
> > don't buy you anything by themselves. There is still the potential for
> > loops if the BGP path doesn't match the OSPF one. Matching isn't even
> > possible with protocols such as RIP and EIGRP so that makes it even
> > stranger. Am I missing something here?
> >
> >
> >
> > From:
> > Divin Mathew John <divinjohn_at_gmail.com>
> > To:
> > Marcel Lammerse <m.lammerse_at_mac.com>
> > Cc:
> > Cisco certification <ccielab_at_groupstudy.com>
> > Date:
> > 02/12/2010 11:17 PM
> > Subject:
> > Re: BGP/OSPF router-id mismatch and the BGP synchronization rule
> > Sent by:
> > <nobody_at_groupstudy.com>
> >
> >
> >
> > Check this out. http://www.internetworkexpert.com/rfc/rfc1403.txt
> >
> > > 3. BGP Identifier and OSPF router ID
> > >
> > > The BGP identifier MUST be the same as the OSPF router id at all
> > > times that the router is up.
> > >
> > > This characteristic is required for two reasons.
> > >
> > > i Synchronisation between OSPF and BGP
> > >
> > > Consider the scenario in which 3 ASBRs, RT1, RT2, and RT3,
> > > belong to the same autonomous system.
> > >
> > >
> > > +-----+
> > > | RT3 |
> > > +-----+
> > > |
> > >
> > > Autonomous System running OSPF
> > >
> > > / \
> > > +-----+ +-----+
> > > | RT1 | | RT2 |
> > > +-----+ +-----+
> > >
> > >
> > > Both RT1 and RT2 have routes to an external network X and
> > > import it into the OSPF routing domain. RT3 is advertising
> > > the route to network X to other external BGP speakers. RT3
> > >
> > >
> > >
> > > Varadhan [Page
> 5]
> > >
> > > RFC 1403 BGP OSPF Interaction January
> 1993
> > >
> > >
> > > must use the OSPF router ID to determine whether it is using
> > > RT1 or RT2 to forward packets to network X and hence build
> the
> > > correct AS_PATH to advertise to other external speakers.
> > >
> > > More precisely, RT3 must determine which ASBR it is using to
> > > reach network X by matching the OSPF router ID for its route
> > > to network X with the BGP Identifier of one of the ASBRs,
> and
> > > use the corresponding route for further advertisement to
> > > external BGP peers.
> > >
> > > ii It will be convenient for the network administrator looking
> at
> > > an ASBR to correlate different BGP and OSPF routes based on
> > > the identifier.
> > >
> > >
> > On Sat, Feb 13, 2010 at 6:16 AM, Marcel Lammerse <m.lammerse_at_mac.com>
> > wrote:
> >
> > > Hi all,
> > >
> > > I know this is not common these days, as BGP synchronization is turned
> > off
> > > by default in recent ios versions. However, I was wondering if anyone
> > knows
> > > why a Cisco router considers an OSPF route not synchronized, if the
> OSPF
> > > router id and BGP router id don't match.
> > >
> > > Is this an implementation-specfic thing or is there some protocol
> design
> > > thinking behind it?
> > >
> > >
> > > Blogs and organic groups at http://www.ccie.net
> > >
> > >
> _______________________________________________________________________
> > > Subscription information may be found at:
> > > http://www.groupstudy.com/list/CCIELab.html
> > >
> > >
> > >
> > >
> > >
> > >
> > >
> > >
> >
> >
> > --
> >
> > Sent from Doha, Qatar
> >
> >
> > 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
> >
> >
> >
> >
> >
> >
> >
> >
>
>
> --
> Cheers,
>
> Jared Scrivener
> CCSI #30878, CCIE3 #16983 (R&S, SP, Security)
> www.MicronicsTraining.com <http://www.micronicstraining.com/>
> Sr. Technical Instructor
>
> YES! We take Cisco Learning Credits!
> Training And Remote Racks available
>
> LinkedIn:www.linkedin.com/in/jaredscrivener
>
>
> 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
>
> _______________________________________________________________________
> Subscription information may be found at:
> http://www.groupstudy.com/list/CCIELab.html
>
>
>
>
>
>
>
>

-- 
Narbik Kocharians
CCSI#30832, CCIE# 12410 (R&S, SP, Security)
www.MicronicsTraining.com
Sr. Technical Instructor
YES! We take Cisco Learning Credits!
Training And Remote Racks available
Blogs and organic groups at http://www.ccie.net