From: Bogdan Sass (bogdan.sass@catc.ro)
Date: Wed Sep 10 2008 - 10:21:59 ART
Nitro Drops wrote:
> How come after R3 peers with R2 and R1, R3 is able to learn prefixes from both
> the peers, after a while, it reduces to just only from one peer? The prefixes
> learnt shows everything are the same in terms of metrics, local preferences,
> weight and path.
>
> Does it means, when the same prefix is learnt from 2 different peers, which
> are of the same equal values, only one can exist?
>
There is no such thing as "equal values" in bgp. Take a look at the
BGP best path selection algorithm here:
http://www.cisco.com/en/US/tech/tk365/technologies_tech_note09186a0080094431.shtml
You will notice that after the router exhausts the "usual"
attributes (weight, local preference, AS path, etc), it will begin using
various other factors as tie-breakers (lowest router ID, lowest neighbor
address, and so on). In the end, there can be only one ;) (at least with
the default configurations)
-- Bogdan Sass CCAI,CCNP,CCSP,JNCIA-ER Information Systems Security Professional "Curiosity was framed - ignorance killed the cat"Blogs and organic groups at http://www.ccie.net
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