Re: Query on BGP path selection

Here is the answer I provided some time ago:
http://www.groupstudy.com/archives/ccielab/200912/msg00789.html to the exact
same confusing scenario.

Regards,

Nicolas
http://ccie-en-espanol.blogspot.com/

On Thu, Jan 14, 2010 at 10:51 AM, Nikhil Engineer <ccienovice_at_gmail.com>wrote:

> Hi Pratik,
>
> As per my understanding in your scenario you have:-
> R1 and R2 is AS6554
> R3 abd R4 in AS6559
> 172.16.1.0 is originated in 172.16.1.0
> R3 is configured with MED value 4000 and R4 is configured with MED value 0.
> R1 is setting local pref of 200 for all the routes received by R3
> R2 is setting local pref of 100 for all the routes received by R4.
>
> Lets consider x route is originiated in AS6559.
> In this case,
> R1 and R2will have x.x.x.x two routes one with LP200 and MED4000 while
> another with LP100 and MED0.
>
> 172.16.1.0 will prefer R1-R3 path cause it has lower LP as LP comes before
> MED.
>
> Hope this is the scenario you were trying to create.
>
> Cheers,
> Nicky
> HTH
>
> On Sun, Dec 13, 2009 at 10:44 PM, pratik bendke <pratikbendke_at_gmail.com
> >wrote:
>
> > Hi Frd's
> >
> > Having query in EBGP the scenario is
> >
> > eg:-
> > R1(local preference 200)
> ----------------!------------------
> > R3(MED 4000) R1-R3 DIRECTLY CONECTED
> > !
> > AS 6554 !
> > AS 6559
> > 172.16.1.0 !
> > !
> > !
> > R2(Local preference 100)
> ----------------!------------------
> > R4(MED 0 default) R2-R4 DIRECTLY CONECTED
> >
> >
> > R1 & R2 in same AS 6554
> > R3 & R4 in same AS 6559
> >
> > Now query is ntwork 172.16.1.0 take which path to reach router in AS
> 6559
> >
> > Path R1 - R3 ? OR
> > Path R2 - R4 ?
> >
> >
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Received on Thu Jan 14 2010 - 11:05:26 ART