From: Pavel Bykov (slidersv@gmail.com)
Date: Fri Nov 28 2008 - 03:08:32 ARST
I think what Scott meant, that there will still be packet loss since when
you make interface passive, the hello timers will expire and OSPF (and other
protocols for that matter) will reconverge as if the links went down. During
table rewrites you will have packet loss.
What I do before migrations, is change cost/delay on the link so in a minute
or so there will be almost-zero traffic on it. Then it doesn't matter if I
use passive or take out interface altogether.
On Fri, Nov 28, 2008 at 3:54 AM, Scott Morris <
smorris@internetworkexpert.com> wrote:
> Semantics. :) That is indeed true. It's FASTER, but it just doesn't seem
> graceful. Ah well.. But yes, I understand the semantics of that speed!
>
> Scott
>
> -----Original Message-----
> From: Marko Milivojevic [mailto:markom@markom.info]
> Sent: Thursday, November 27, 2008 4:27 PM
> To: Scott Morris
> Cc: GAURAV MADAN; Cisco certification
> Subject: Re: Graceful shutdown : OSPF
>
> On Thu, Nov 27, 2008 at 19:50, Scott Morris <
> smorris@internetworkexpert.com>
> wrote:
> > You could do passive for the interface (in router ospf config), or on
> > the interface itself you can use "no routing dynamic"
> >
> > I'm not sure I'd consider either to be particularly "graceful" though.
>
> They actually are... at least much more than simply shutting down the
> interfaces ;-).
>
> It takes time for neighbors and LSA's to be cleared from the tables and run
> SPF to recalculate paths and update RIB. If you are using boxes with
> separate forwarding plane, it takes even longer! At the same time, CEF
> table
> is intact and router keeps forwarding traffic out the interfaces on which
> you disabled OSPF. When recalculation is finished and CEF is updated,
> traffic will shift traffic to alternative interfaces, or alternative
> routers
> altogether.
>
> I use this all the time when upgrading backbone nodes.
>
> --
> Marko
> CCIE #18427 (SP)
> My network blog: http://cisco.markom.info/
>
>
> Blogs and organic groups at http://www.ccie.net
>
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-- Pavel Bykov ---------------- Don't forget to help stopping the braindumps, use of which reduces value of your certifications. Sign the petition at http://www.stopbraindumps.com/Blogs and organic groups at http://www.ccie.net
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