[c-nsp] delay eBGP sessions on startup?

Gert Doering gert at greenie.muc.de
Mon Nov 23 03:10:25 EST 2009


Hi,

On Mon, Nov 23, 2009 at 08:46:56AM +0100, Gert Doering wrote:
> One possible solution would be to have a knob that tells IOS "delay bringing
> up eBGP sessions and/or announcement of routes on eBGP sessions for <n>
> seconds after initial BGP startup".  This would make sure that iBGP has
> converged before eBGP starts, and no transient black-holing is seen.

Indeed there is a knob that seems to go into the right direction
(thanks to Marco Eulenfeld for pointing this out to me):

  "bgp update-delay <n>" 

"the bgp update-delay command is used to tune the maximum time the software
will wait after the first neighbor is established until it starts calculating
best paths and sending out advertisements".

Now, what does "maximum time" mean?  Will it wait, or will it not?

The documentation that I found claims that the default value is "120",
which would certainly not agree with the observed behaviour.  OTOH, Marco
claims that he has seen "0" as a default...

Will test, and report.

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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