From: Asim Khan (asimmegawatt@yahoo.com)
Date: Sun Sep 22 2002 - 15:44:32 GMT-3
thats fine, but the question here is AS20 wants to
send its traffic through Link 2 and AS10 wants all
traffic from AS20 comes through Link 1.
--- "Steven A. Ridder" <saridder@attbi.com> wrote:
> Incoming and outgoing traffic are treated
> separately.
>
> -----Original Message-----
> From: nobody@groupstudy.com
> [mailto:nobody@groupstudy.com] On Behalf Of
> Asim Khan
> Sent: Sunday, September 22, 2002 11:59 AM
> To: ccielab@groupstudy.com
> Subject: Basic BGP decision process
>
>
> Hi all,
>
> Suppose we have 4 routers Ra, Rb, Rc and Rd. Ra is
> in
> AS10 and Rb, Rc and Rd are in AS20 as shown below:
>
> AS10
> | loopback 1.1.1.1/32
> |
> Ra
> / \
> Link 1 / \Link 2
> -------------------------------
> / \
> Rc Rb
> AS20 \ /
> \ /
> \ /
> \ /
> Rd
> Now suppose the Administrator of AS20 wants all
> outgoing traffic to take Link 2, so he set the local
> preferance on Rb for incoming routes (1.1.1.1) from
> Ra
> as 200 and on Rc as 100(default). Rb,Rc and Rd are
> in
> full meshed. It means to reach 1.1.1.1 router Rd
> will
> take the path of Link 2. Now the administrator of
> AS10
> wants to influence the incoming traffic from AS20
> and
> force them to use Link 1. So he set the MED 5 for
> all
> the outgoing routes via Link 1 and the MED 10 for
> all
> the outgoing routes via Link 2.
>
> I know in BGP decision process local preference
> comes
> first then MED and in general BGP policies establish
> after mutual consultation of both the Administrator.
>
>
> But in this particular case, when both the
> administrator are in complete disagreement, which
> link
> will be used for traffic going from AS20 to AS10.
>
> If Link 2 is used then is there any way for
> Administrator of AS10 to force AS20 to use Link 1.
>
> Regards.
>
> Asim Khan
>
>
>
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