Consistent routing policy?

Mon Sep 16 19:55:55 UTC 2019

Peace,

On Mon, Sep 16, 2019, 12:04 PM Owen DeLong <owen at delong.com> wrote:

> For any router which receives both announcements, longest match always
> wins over all other BGP tie-breaking criteria.
>
> This is almost always summarized as “Longest Match always wins” because
> virtually any engineer recognizes that the
> winner is selected only from the available contestants, not from unknown
> distant contestants not present at the router
> in question.
>

The point is that you must expect inbound traffic to any prefix you
advertise to the outside world, even a more specific announcement is also
being advertised.  There are legitimate circumstances where an ISP would
prefer the super-block.

--
Töma
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