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