Re: ASBR Selection

Vincent,
OSPF does not have a split horizon rule like RIP or EIGRP. Can you send us
the "show ip route" of R2? I'm guessing that the routes you are talking
about are EIGRP external routes. In that case R2 will have that EIGRP route
as AD 170 in EIGP and 110 from OSPF (via R3). In that case it will prefer
the route from OSPF and will no redistribute it back to OSPF.

Regards,

Tom

On Mon, May 28, 2012 at 7:39 AM, Vincent Tay <vtay.75_at_gmail.com> wrote:

> Hi Brian/all,
>
> Thanks. For the topology below, can i conclude it as if R3 (ASBR) is
> sending the updates of the redistributed EIGRP routes to R2 (ASBR), R2
> (ASBR) will not resend these learn routes back out the same interface as it
> is receive on. Therefore, there will be no loops between R3 and R2.
>
> > >> EIGRP
> > >> ____________________________________
> > >> | |
> > >> | |
> > >> | |
> > >> R3(ASBR)------------------------------R2(ASBR)
> -> Redistributing EIGRP into OSPF
> > >> | |
> > >> | |
> > >> | |
> > >> OSPF Area Routers
> > >> ___________________________________
> > >>
> Regards
>
> On Mon, May 28, 2012 at 9:59 PM, Brian McGahan <bmcgahan_at_ine.com> wrote:
>
> > Take a look at this writeup on Understanding OSPF External Path
> Selection:
> > http://goo.gl/pxx1p
> >
> > Brian McGahan, CCIE #8593 (R&S/SP/Security)
> > bmcgahan_at_INE.com
> >
> > Internetwork Expert, Inc.
> > http://www.INE.com
> >
> >
> > -----Original Message-----
> > From: nobody_at_groupstudy.com [mailto:nobody_at_groupstudy.com] On Behalf Of
> > Vincent Tay
> > Sent: Monday, May 28, 2012 8:16 AM
> > To: Tony Singh
> > Cc: oo IPX; Ccielab_at_groupstudy.com
> > Subject: Re: ASBR Selection
> >
> > Hi all,
> >
> > I have lab it up. Both ASBR is redistributing E2 cost 20 metric. However,
> > the highest router-id wins does not apply. For example, if i clear ip
> ospf
> > process on R3, R3 will be the ASBR. If i clear the other fellow R2, R2
> > become ASBR. So, i was confused.
> >
> > Regards
> >
> > On Mon, May 28, 2012 at 8:59 PM, Tony Singh <mothafungla_at_gmail.com>
> wrote:
> >
> > > Is it not the case if we have two asbr's that we need to specify type
> > > 1 in redistribution this is enable router to make correct decision for
> > > packet forwarding for the destination? Please correct me
> > >
> > > --
> > > BR
> > >
> > > Sent from my iPhone on 3
> > >
> > > On 28 May 2012, at 11:13, oo IPX <oispxl_at_gmail.com> wrote:
> > >
> > > > and say R2 and R3 are receiving *E2 routes * then the *lower*
> > > *forwarding
> > > > metric path is chosen. *
> > > >
> > > > if one is E1 and other comes from E2, no matter what the cost is, E1
> > > > will be preferred.
> > > >
> > > >
> > > >
> > > >
> > > > On Mon, May 28, 2012 at 2:21 PM, Vincent Tay <vtay.75_at_gmail.com>
> > wrote:
> > > >
> > > >> Hi all,
> > > >>
> > > >> If there are two ASBRs redistributing routes, will there be any
> > > selection?
> > > >> From what i have try, the router that i clear the ospf process will
> > > >> end
> > > up
> > > >> advertising the type 5 routes. I am quite confuse with it.
> > > >>
> > > >> EIGRP
> > > >> ____________________________________
> > > >> | |
> > > >> | |
> > > >> | |
> > > >> R3(ASBR)------------------------------R2(ASBR) !
> > > >> Redistributing EIGRP into OSPF
> > > >> | |
> > > >> | |
> > > >> | |
> > > >> OSPF Area Routers
> > > >> ___________________________________
> > > >>
> > > >> Thanks.
> > > >>
> > > >>
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> > > >>
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Received on Mon May 28 2012 - 09:25:46 ART