From: Brian McGahan (brian@xxxxxxxxxxxxxxx)
Date: Tue Aug 20 2002 - 21:35:53 GMT-3
Thai,
The BGP decision process is:
Weight
Local-Preference/locally originated
AS-Path
Origin code
MED
EBGP over iBGP
Shortest internal path
Router-ID (lowest)
Based on this decision process, the reason R3 is routing towards
R1 is the AS-PATH. Distance doesn't come into play until you try to
install the route in the routing table. BGP best-path selection
determines which path is best in the BGP table, not which appears in the
IP routing table.
Based on this, it should be fairly obvious which attribute you
need to modify (I hope). If not, review Halabi's book or Doyle vol 2 to
see how these attributes function.
For more info on BGP bestpath:
http://www.cisco.com/warp/public/459/25.shtml
HTH
Brian McGahan, CCIE #8593
Director of Design and Implementation
brian@cyscoexpert.com
CyscoExpert Corporation
Internetwork Consulting & Training
http://www.cyscoexpert.com
Voice: 847.674.3392
Fax: 847.674.2625
> -----Original Message-----
> From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf
Of
> Nguyen, Thai
> Sent: Tuesday, August 20, 2002 6:40 PM
> To: 'ccielab@groupstudy.com'
> Subject: BGP Challenge
>
> Hi all,
>
> I've been working on this little problem for few days but have not
been
> able
> to crack it.
> Can anyone shed light into this please?
>
>
>
> R1============R2
> = =
> = =
> = =
> = =
> ========R3
>
>
> R1 is in AS 1
> R2 and R3 is in AS2
>
>
> R1 is advertsing a subnet eg 1.1.1.0/24. Normally R3 will have to path
to
> the network, first via R1 directly and second via R2.
> And the preferred path is via R1 because the administrative distance
of
> the
> route learning from R1 is 20 while the route learned via R2 is 200.
>
> The challenge of the excercise is to configure R2 so that R3 would
> prefered
> the route it learned from R2 without additional configuration on R3.
>
> regards
>
>
> Regards,
>
>
>
>
>
>
>
>
>
>
>
>
>
>
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