[c-nsp] Best practice for lowest convergence time when rebooting router

[Gert Doering]

Hi,

On Mon, Oct 13, 2008 at 11:01:01PM -0400, Jay Nakamura wrote:
> Quick question,
> 
> Does anyone do anything special before rebooting/shutting down a core or
> border router so routes on other routers converge faster around the rebooted
> router?  I was thinking if it would be better if I heavily BGP prepend to
> upstream first so bordering peer router will still route to me until the
> better route from the other upstream propagated to that peer.  What about
> OSPF inside our network?  Putting the interfaces in passive mode first?

What we do is:

 - shutdown all eBGP sessions (but leave the interfaces "up") - so while
   the control plane converges, packets can still travel via that router

   [this could be made a bit smoother by prepending / de-local-pref'ing
   the routes first, but shutting down the BGP session before bringing down
   the interface is smoother already than hard reloading]

 - make internal routing 'passive' on all but one interface - so the iBGP
   sessions can still be up, but other routers won't consider this router
   for packets, as there are not IGP paths "across" it

 - reload

 - wait for iBGP to come back and converge

 - bring back eBGP

 - bring back IGP

(now this is something why I'm really really really tempted to switch to
IS-IS, the "overload" bit, making the 'bootup smoothly' process automatic)

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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