Re: The Cidr Report

["Christopher L. Morrow" <christopher.morrow () mci com>]

On Sat, 12 Feb 2005, Alexander Koch wrote:

> On Sat, 12 February 2005 14:58:42 +0000, Stephen J. Wilcox wrote:
> > From: "Stephen J. Wilcox" <steve () telecomplete co uk>
> > [...]   - would you agree that most of the poor deaggregating is not intentional
> > ie that they're announcing their '16 class Cs' or historically had 2 /21s and
>
> Think about someone putting in a Null0 route and re-
> exporting stuff unconditionally, now after he originates
> his /19 he is then adding a /24 here, and a /25 there.
> Lack of experience, when you suggest to them they should
> remove these announcements they are afraid to change it,
> not understanding the implications, etc.
>
> Not to mention ppl using cisco and prefix lists, it is
> way too easy with cisco to say '/19 le 24', and then they
> use outbound prefix lists to their transit supplier
> (different, but related as I see it). Some transit ISPs
> use that a lot, and encourage the table growth.

There are some business reasons to de-aggregate. Look at some outages
caused by 'routing problems' (someone leaked my /24's to their peers,
peers, peer and my traffic got blackholed, because the public net only
knows me as a /20)

There are multiple reasons for deaggregation aside from 'dumb operator',
some are even 'valid' if you look at them from the protection standpoint.

-Chris