From: Nick Shah (nshah@xxxxxxxxxxxxxx)
Date: Tue Jul 09 2002 - 05:30:27 GMT-3
Donny
What Hansang means is that "in some production environments" we override
communities, or ignore communities from certain customers (less popular in
ISP/NSP environment).
So its not a sure shot way to ascertain that the community attribute would
be honored. Because you cannot guarantee that ur upstream will not over ride
community or not accept community (not honor actually).
However in a lab/controlled environment as this, where there are 3 (or more)
routers involved (RtrA --- RtrB ---- RtrC) we can either put a prefix
filter/distribute list on B (outbound towards RtrC) or set community
no-export on RtrA. This will depend mostly on which options are allowed and
which options are not. It will also depend upon which Router you are allowed
to make changes on. Say RtrA is a backbone router over which you have no
control, your options are pretty much prefix filter or distribute list on
RtrB, basically not allowing the route to leak to RtrC. However if you are
having control on RtrA, then you could use community, which in my opinion is
*slightly cleaner*
rgds
Nick
----- Original Message -----
From: Donny MATEO <donny.mateo@sg.ca-indosuez.com>
To: Hansang Bae <hbae@nyc.rr.com>
Cc: <ccielab@groupstudy.com>; <nobody@groupstudy.com>
Sent: Tuesday, July 09, 2002 4:26 PM
Subject: Re: As Transit
> Could you please elaborate more on "the other side does not *have* to
honor
> it" ?
> As far as I know ( do correct me if I'm wrong) all IBGP peer would have
the
> same comunities attribute set and as far as the effect is that the routes
> won't be propagated to external peers (EBGP), and that should (again
> correct me if I'm wrong) achieve the objective of not advertising route
> learned from external peer to other external peer(s).
>
> Thanks.
> Donny
>
>
>
> Hansang Bae
> <hbae@nyc.rr.com> To:
ccielab@groupstudy.com
> Sent by: cc:
> nobody@groupstudy Subject: Re: As Transit
> .com
>
>
> 09-07-2002 13:50
> Please respond to
> Hansang Bae
>
>
>
>
>
>
> At 12:52 PM 7/9/2002 +0800, Donny MATEO wrote:
> >How about community no-export when you receive the route
> >Something like
> >router bgp x
> > neighb x.x.x.x route-map SETCOM in
> >end
> >route-map SETCOM permit 10
> > set community no-export
> >end
>
>
> The problem with communities is that the other side does not *have* to
> honor it.
>
> I'd go with what others suggested.
>
>
> hsb
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