On Mon, 28 Apr 2003, Rob Thomas wrote:
] | If you ask providers, they all say they implement positive prefix ] | list filters on all their customers. ] ] That isn't my (recent) experience at all. Quite the reverse, in fact!
Agreed. When I was working for a hosting provider, the filters were inconsistently applied even within the disparate pipes purchased from the same provider. It really depended entirely on the ISP engineer who configured the link. This was the case with multiple providers.
Why do we expect the same ISP engineers to be better at configuring negative lists or keeping them up to date?
According to Craig Labovitz's study published at Microsoft http://www.research.microsoft.com/research/pubs/view.aspx?msr_tr_id=MSR-TR-2... 100% of the ISP's surveyed filter inbound customer route announcements.
Ahhh, but that was not the correct question to ask (I have not read the study). It is not whether ISP's filter inbound customer route announcements. It is how they filter them. If the customer goes and says I am going to announce 4.0.0.0/8 and the ISP just blindly adds that to the filter, we have a problem, but the ISP did answer that question truthfully. They are filtering. jon