From: YourPal (dearprudence28@gmail.com)
Date: Thu Mar 13 2008 - 08:36:27 ARST
Hi All,
Those 3 prefixes are loopback addresses of the respective router. They are
not advertised in IGP.
An earlier task asks to advertise those loopbacks into BGP with no
restriction. Then comes this task that restricts configuration on R1 only.
Is it possible at all? I still think that we need to configure something on
R2 (whether setting MED, community, origin code, etc) in order to satisfy
this task, if that's allowed at all.
Thank you.
BR,
Emil
On 3/13/08, Shine Joseph <shinepjoseph@iprimus.com.au> wrote:
>
> Emil,
>
> The fact that origin code is ahead of MED in best path calculation, you
> can
> change the origin code to accomplish this task.
>
> If there is no restriction in how you advertise the networks in AS123, I
> can
> think of advertising the network with origin code of igp to R4 from R1. If
> you are restricted with no-redistribution, then apply a route-map in the
> network statement to change the origin code to incomplete.
>
> I have labbed up your scenario and it works.
>
> HTH,
> Shine
>
>
> -----Original Message-----
> From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf Of
> YourPal
> Sent: Thursday, 13 March 2008 5:19 PM
> To: Cisco certification
> Subject: Question on Influencing BGP Inbound Path Selection
>
> Hi Group,
>
> I came across the following BGP scenario:
>
> R1, R2, and R3 are in AS 123. They are fully-meshed. R4 is in AS 456. R4
> peers with R1 and R2.
>
> R1 advertises 172.16.1.1/32 into BGP.
> R2 advertises 172.16.2.2/32 into BGP.
> R3 advertises 172.16.3.3/32 into BGP.
>
> Configure R1 so that R4 prefers R1 to reach 172.16.1.1/32 and
> 172.16.3.3/32.
> Route filtering and AS path manipulation are prohibited.
>
> The way I see it, I'm left with the option of configuring MED. However
> since
> the task restricts the config to be done on only R1, AFAIK there's no way
> to
> influence MED because both R1 and R2 will advertise the prefixes to R4
> with
> MED=0 (unless I'm allowed to configure a higher MED value on R2).
>
> Can't think of a solution. I may be missing something. Appreciate any
> help.
>
>
> Thank you.
>
> BR,
> Emil
>
> _______________________________________________________________________
> Subscription information may be found at:
> http://www.groupstudy.com/list/CCIELab.html
This archive was generated by hypermail 2.1.4 : Tue Apr 01 2008 - 07:53:53 ART