Re: [nsp] BGP Multihoming -how to announce backup route???

From: Gert Doering (gert@greenie.muc.de)
Date: Wed Nov 21 2001 - 17:58:42 EST


Hi,

On Wed, Nov 21, 2001 at 06:51:41PM +0100, sthaug@nethelp.no wrote:
> > > Bzzzt. Still wrong. There's nothing to stop anyone with an ARIN /20
> > > announcing smaller blocks.
> >
> > No. But there is nothing either that is going to force *me* to ever
> > increase my router's CPU and memory. If those people want to be reached,
> > they can announce the /20. If they do not want, they can announce it
> > as /32s (which would be ridiculous, but then, where is the border to
> > "ridiculous"?).
>
> I think this is pretty ridiculous, actually:
>
> *>i24.154.32.0/24 213.239.22.241 200 0 8918 701 7046 ?
> *>i24.154.33.0/24 213.239.22.241 200 0 8918 701 7046 ?
> *>i24.154.34.0/24 213.239.22.241 200 0 8918 701 7046 ?
> *>i24.154.35.0/24 213.239.22.241 200 0 8918 701 7046 ?

[ Lots of ugly things snipped... ]

Yes, these are like what I'm talking about. I cannot see a single reason
why it is "necessary" that those prefixes are visible on *my* routers,
and everybody elses in the whole world.

Even if 7046 has multiple links to 701, it would be possible to send
out a /20 *and* all the /24s, and tag the /24s as "do not export
elsewhere".

> Or this:

Same game, only a /19 this time...

> Plenty more among the current 105k routes...

Yes. Phil's statistics lists 61536 /24s as of last week. While he
doesn't list "how many of those are aggregateable", he *does* list the
following scary number:

"Total number of prefixes smaller than registry allocations: 73802"

this means: 73,000 prefixes are there that are more specific than what the
registries allocate, read: "that are likely to be aggregateable to a LOT
less".

gert

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



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