From: Smith, Jason (JASmith@nuvox.com)
Date: Mon Apr 07 2008 - 20:06:15 ART
Does BB1 and BB2 advertise the same routes??
Thanks,
Jason Smith
-----Original Message-----
From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf Of
Chris McGuire
Sent: Monday, April 07, 2008 5:27 PM
To: Peter Grewal; 'Cisco certification'
Subject: Re: Question about BGP and setting local preference
This appears to me to be correct. On 1 side you should see both routes
in
the BGP table. On the other you should see only 1. What happens is R2
receives both routes. It then chooses the best route and installs it
into
it's Route table. If the "Best" route is coming from R1, it will forward
that route on to R3. If the "Best" route is coming from R3, it will
forward
that route on to R1. R2 will not take a route from R3 and forward it on
to
R1 if it is not a route that it can install in it's own route table. So
on 1
side, you should only see 1 route - the EBGP route. ON the other, you
should
see the EBGP route and 1 IBGP route in the bgp table. Unless I am
missing
something, you are seeing it work as it should.
-Chris
On 4/7/08 1:06 PM, "Peter Grewal" <peter@avient.ca> wrote:
> Just trying to figure out something that I'm seeing in BGP, and
determine
> whether its normal behavior or not.
>
>
>
> Suppose I have routers BB1----R1 --------R2-----R3----BB2
>
>
> |
>
>
> R4
>
>
>
> R1, R2, R3, R4 are all in the same AS, BB1 and BB2 are in the same AS.
I
> have applied a local preference specifying all routes learned from the
> external AS are preferred through R3 with a value of 200, routes
learned
> from R1 have a local pref for the external AS specified to 150. After
> applying the corresponding access list to both R1 and R3, when I
perform a
> show IP BGP on R3 I no longer see routes for that are advertised by
BB1
> through R1. Is this normal behavior ???
>
>
>
> Thank you.
>
>
>
> Peter.
>
>
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