[c-nsp] BGP conditional advertisement

[Gert Doering]

Hi,

On Wed, Aug 28, 2013 at 11:22:06PM +0300, Ahmed Hilmy wrote: > Hi Friends,
> when i force prefix Z to be advertised to ISP A only and to ISP B only when
> ISP A is down.
> does my end customer will face an outage or a flap ?  

Of course.  While BGP is converging, the link to A is broken and B is not
yet active, and C-behind-B will not see the advertisement for even longer.

> i want that the
> recovery time should be fast enough that the customer will not be able to
> sense it.

Announce your prefixes to all upstreams all the time, do not change
announcements on a whim (as in "take instability on A, make it into
instability on B").

> Does  conditional advertisement do that ?

Understand BGP.

Understand "convergence" and "routing propagation", then reexamine what
you want to achieve.

(And *please* learn to quote)

gert
-- 
USENET is *not* the non-clickable part of WWW!
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Gert Doering - Munich, Germany                             gert at greenie.muc.de
fax: +49-89-35655025                        gert at net.informatik.tu-muenchen.de
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