From: Ash (nester2k@gmail.com)
Date: Fri Aug 24 2007 - 11:54:07 ART
If you do it directly from the network command, just like you pointed out ,
it wont leave the origin AS.
But your goal is to prevent this route from being propagated beyond AS 54
which means that this network atleast needs to be advertised to the AS 54
and then the ' no-export treatment' needs to follow. Thus, configuring a
route-map outbound on the neighbor and tagging the route with no export and
sending the community is the way to go.
On 8/24/07, Toh Soon, Lim <tohsoon28@gmail.com> wrote:
>
> Hi nicky noname,
>
> I'm sorry I don't fully understand what you said.
>
> Anyway looking at your config and based on my understanding, R1 will
> install
> 150.12.66.0/24 into its BGP table and tag it with community of no-export.
> R1
> will not advertise it to BB1. You don't even need the command "neighbor
> BB1
> send-community".
>
> Over at R2, you can do "sh ip b com no-ex". You should see the
> 150.12.66.0/24 route. R2 will honor the no-export community by not
> advertising it to BB2. Again, you don't need the command "neighbor BB2
> send-community".
>
> Anyone any comments? Do correct me if I'm wrong. I have not labbed this
> scenario to confirm.
>
>
> Thank you.
>
> B.Rgds,
> Lim TS
>
>
> On 8/24/07, nicky noname <cisco2study@gmail.com> wrote:
> >
> > Hello,
> >
> > I would very much appreciate some clarification.
> >
> > I have two routers in AS 2 that have two ebgp connections to backbone 1
> > and
> > 2 ( one each) in AS 54.
> >
> > We are to advertise network 150.12.66.0 mask 255.255.255.0 on one router
> 1
> > in AS2.
> >
> > We do not want this network to be advertised past AS54.
> >
> > You can send the community attribute no-export to the backbones from R1
> > and
> > R2, via a route-map matching the network and setting the community and
> > then
> > sending the route-map to AS54.
> >
> > The questions is, can we not also, attach the community of no-export,
> > direct
> > to the network advertisement in BGP on R1, and then send the community
> > also
> > to R2 and to both Backbone 1 and 2, without specifically pushing a
> > route-map
> > out to the backbones ( just sending the community attribute) ?
> >
> > I have attached the later example...it would appear that the prefix will
> > not
> > leave the local AS?
> >
> >
> >
> >
> >
> > #################################
> > R1
> >
> > router bgp 2
> > no synchronization
> > bgp router-id xxxx
> > bgp log-neighbor-changes
> > neighbor R2 remote-as 2
> > neighbor R2 send-community
> > neighbor BB1 remote-as 54
> > neighbor BB1 send-community
> > network 150.12.66.0 mask 255.255.255.0 route-map no-export
> > no auto-summary
> > !
> > route-map no-export permit 10
> > set community no-export
> > !
> > ##########################
> > R2
> >
> >
> > router bgp 2
> > no synchronization
> > bgp router-id xxxx
> > bgp log-neighbor-changes
> > neighbor R1 remote-as 2
> > neighbor BB2 remote-as 54
> > neighbor BB2 send-community
> >
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