From: Pavel Bykov (slidersv@gmail.com)
Date: Tue Jan 13 2009 - 11:59:15 ARST
It's extremely important where you set the attribute in this example and
direction of the update. If the update travels R1>R2>R3, then:
1. NO-ADVERTISE:
- If you set it on R1 directly (like network x.x.x.x route-map XYZ), R2 will
not receive route.
- If you set it on R1 as route-map to R2, R2 will receive and use route, but
will not advertise it to R3
- If you set it on R2, R3 will use route, but will not advertise it to any
other neighbor.
2. NO-EXPORT:
If you set it on R1, R2 will receive and use route, but will not advertise
it to R3 (route will stay in AS 10)
If you set it on R2, R3 will receive and use route, but route will not get
out of AS 30
3. LOCAL-AS:
Same as no-export, but also valid for BGP confederations.
On Mon, Jan 12, 2009 at 10:57 PM, Jason Morris <mcnever@gmail.com> wrote:
> for local-as to work you would have to set that community inbound on
> R3. If that's out of your domain that's not really an option. If you
> set the local-as community while its still inside AS10 it wont get
> advertised out.
>
> no-export = AS10 telling AS30 not to tell anyone else
>
> local-as = AS10 not telling AS30 at all
>
> or at least that's my understanding
>
>
>
>
> On Mon, Jan 12, 2009 at 3:27 PM, CCIE To Be <ccie.tobe81@gmail.com> wrote:
> > Got it....
> >
> > Other question is related to local-as community. Let suppose we don't
> want
> > to advertise a specific prefix outside 'AS 10' then we will have again
> same
> > option of no-export. What about using local-as community in this scenario
> > which will not allow a particular prefix to go out of local AS 10 ??
> >
> >
> >
> > On Tue, Jan 13, 2009 at 12:01 AM, Huan Pham <pnhuan@yahoo.com> wrote:
> >
> >> No-export of course!
> >>
> >> Using no-advertise will prevent prefixes received from AS10 to be
> >> advertized to R3 iBGP peers as well which are undesirable here.
> >>
> >> Sent from my iPhone
> >>
> >> On 13/01/2009, at 6:28 AM, CCIE To Be <ccie.tobe81@gmail.com> wrote:
> >>
> >> Dear Group,
> >>
> >> I have a confusion regarding usage of no-advertise and no-export
> >> communities. I know that no-advertise means NOT TO ADVERTISE to any bgp
> >> peer
> >> ( iBGP & eBGP ) whereas no-export says NOT TO ADVERTISE to any eBGP peer
> >> means don't advertise outside this AS. Consider the following topology,
> >>
> >> R1(AS 10) --------R2(AS 10)------------R3(AS 30)
> >>
> >> Let say AS 10 is advertising a prefix to AS 30 and requirement is that
> AS
> >> 30
> >> should not forward this prefix further to any other AS. Now we have
> option
> >> to use either no-advertise or no-export on R2 towards R3. Both will give
> >> the
> >> desired result , what should be the recommended approach here ??
> >>
> >>
> >> HTH
> >>
> >>
> >> Blogs and organic groups at http://www.ccie.net
> >>
> >> _______________________________________________________________________
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> >
> >
> > 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
>
>
>
>
>
>
>
>
-- Pavel Bykov ---------------- Don't forget to help stopping the braindumps, use of which reduces value of your certifications. Sign the petition at http://www.stopbraindumps.com/Blogs and organic groups at http://www.ccie.net
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