Re: bgp problem

Just to add to what Bob has already mentioned,

By default, BGP can advertise routes that it could NOT install in the RIB,
when it fails to do so, it gives you a RIB-FAILURE. NOW, the reason in many
cases is pretty obvious, it was injected into the RIB by another routing
protocol that had a better Admin Distance. This is typical when Ibgp is
used, because it has an Admin Distance of 200 which is higher than any IGP's
Admin Distance.

You can change this behaviour, you can actually tell BGP NOT to advertise
the routes that are inactive by using "BGP Suppress-inactive" command, this
will suppress the inactive routes. What are inactive routes? The BESTPATH
routes that BGP failed to install in the RIB and in your case they were
there to begin with, and BGP could NOT do anything about it, because of the
Admin Distance.

But this command will ONLY work if the next-hop IP address through your IGP
is pointing to a different next hop IP address used by BGP. If they are
pointing to the same IP address, this command will NOT work.

You could actually see this in the last column of the "Show ip bgp
rib-failure" output. If the next-hop IP addresses are pointing to the same
IP address, this command will NOT do anything for you, and you need to
change the next hop or the Admin Distance.

On Mon, Aug 30, 2010 at 7:01 AM, Mustafa Yadav <mustafa.yadav_at_gmail.com>wrote:

> Thanks guys.
>
> I saw my mistakes .In r2( another point I have redistributed bgp into
> ospf).and there ospf routes in does not effect for r5 table becuase it has
> learn them from R1 e-bgp neigbhor.
>
> But the same routes comes to r1 and the strange thing happened.R1 learned
> these routes via ibgp neigbor which ad is 170.Since ospf ad is 110 in R1
> I
> have got rib failure.
>
>
>
> On Mon, Aug 30, 2010 at 4:54 PM, Ryan West <rwest_at_zyedge.com> wrote:
>
> > Mustafa,
> >
> > > -----Original Message-----
> > > From: nobody_at_groupstudy.com [mailto:nobody_at_groupstudy.com] On
> > > Behalf Of Mustafa Yadav
> > > Sent: Monday, August 30, 2010 9:42 AM
> > > To: Cisco certification
> > > Subject: bgp problem
> > >
> > > Hi all,
> > >
> > > I had a strange situation.In R1 some bgp prefixes shown as rip failure
> > but
> > > somehow they have been advertised to R5 .In r5 in routing table they
> > shown
> > > as normal routes came from bgp table.I will go fro a troobleshooting
> but
> > > before I want to knoe .Is it possible for a prefix which has rib
> failure
> > to be
> > > advertised to a ebgp neighbor?
> > >
> > > As far as I know for a prefix to be advertised it has to be chosen best
> > and go
> > > to routing table.Am I wrong?
> > >
> > >
> >
> > The routes are known via your IGP with a lower AD, but are still
> candidates
> > to be advertised to eBGP neighbors.
> >
> > -ryan
>
>
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