Re: BGP Multihoming!

Hello manoj,

Well we can alway control traffic outbound from our AS but we can't control
incoming traffic to our AS the reason being that Weight/Local preference
come before AS-Path Med.Thus by setting weight or local preference you can
always control the traffic coming out of your AS.Incoming traffic can't be
controlled due to the fact that the ISP can set its weight/local preference
in such a way to override your metric/as-path settings.

I believe there are a couple of options. #1 Agree with the ISP that they
will only send routes to you via a certain path, this could be done on the
ISP side. Another option would be to use conditional route advertisement,
i.e. to only advertise the routes to one ISP and when that ISP fails you
would advertise the route to the other ISP. This is known as conditional
route advertisement i.e. you will only advertise the route to the other ISP
when the link to the 1st ISP fails.

Hope this helps!

Best Regards,

On Mon, Feb 1, 2010 at 7:13 AM, manoj prajapati <manoj4784_at_gmail.com> wrote:

> Hello Expert,
>
> Needed a help regarding BGP multi homing case.
> It seems simple at a glance yet somewhat confusing while explanation
>
> ----------------------------------------------
> I have 2 BGP multi homing scenarios....
>
> Case1:
>
> ISP A BGP 200 -----> Customer A "router 1" BGP 100
> ISP B BGP 300 -----> Customer A "router 2" BGP 100
>
> Case2:
>
> ISP A BGP 200 -----> Customer A "router 1" BGP 100
> ISP B BGP 300 -----> Customer A "router 1" BGP 100 (Same router 2
> interfaces)
> ------------------------------------------------------------
> I want that my outgoing "traffic" should be from router A(which we can
> controll by local preference in case 1 or weight in case 2)
> but only ISP B should sent traffice for our AS 100.
>
> How can we achieve that?
>
> Regards,
> Manoj P.
>
>
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-- 
KJ
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