Re: Who is announcing bogons?

[Henry Kilmer <hank () rem com>]

babylon () egenius org writes:
> > 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-2000-74
> > 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.

Many ISPs use AS path filters for customers with a large number of
announcements.  Some implement netblock filters that are not exact
matches.  Both of these are examples where the ISP would honestly say
they filter but holes exist.

-Hank