Re: BGP and AS loop prevention

that shud help. its kinda straight forward. but check whether in as 200
router u have the > "best path"
http://ardenpackeer.com/routing-protocols/bgp-allowas-in-bgp-local-as-tips-and-tricks

On Tue, Oct 20, 2009 at 9:05 AM, ALL From_NJ <all.from.nj_at_gmail.com> wrote:

> I would re-check your setup.
>
> You are right, the allow-as will simply allow in the local AS x number of
> times in the path. This is done on the receiving end.
>
> If you changed your set up some, and one side has the AS 101, is the
> problem
> present? I might suggest to try this and make sure all BGP is cool first.
>
> Also, you can prepend an AS on advertisement, so you can leave the one side
> with AS 101 as is and simply send out a route with AS 100 in the path. The
> AS 100 router should not accept it. This is another way to test the
> allowed-as command.
>
> Create a new loopback on AS 101 and prepend AS 100 in it.
>
> HTH,
>
> Andrew Lee Lissitz
>
>
>
>
>
> On Mon, Oct 19, 2009 at 11:12 PM, Nate Lee <natetlee_at_gmail.com> wrote:
>
> > I have a scenario labbed up where I have an discontiguous BGP AS split by
> > another AS, something like this: (AS100) <> (AS 200) <> (AS 100).
> >
> > I am trying to get the prefixes on the AS 100 routers to show up in each
> > others BGP tables. I have implemented the neighbor x.x.x.x allowas-in
> > command on the AS 100 routers on their neighbor statements facing the AS
> > 200
> > routers but it does not seem to work. When I do a SHOW IP BGP NEIGH
> > x.x.x.x
> > ADVERTISED-ROUTES on the AS 200 routers, I see that the AS 200 router
> will
> > not send the route that originated in the far side AS 100.
> >
> > Is there some sort of configuration needed on the AS 200 routers to allow
> > them to send a route with an AS PATH that contains the AS they are
> sending
> > into? I was under the impression that they do not perform an outgoing AS
> > PATH check.
> >
> > Thanks!
> >
> > Nate
> >
> >
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>
>
> --
> Andrew Lee Lissitz
> all.from.nj_at_gmail.com
>
>
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