RE: Filtering Best Practices, et al (Was Verio Peering, Gordon's Knot)

> > I'm currently in the process of setting up a new border
router, and the
> > recent debate on the above topic got me wondering what
the best practice
> > filtering policy is? Is there one?
> I'm interested to see if people filter route anouncements
on the basis
> of registered routes in an Internet Routing Registry. In our area
> (Europe), the RIPE database typically contains less than half of the
> routes which are actually announced. I assume it is not better in
> ARINland.

When I worked at Tiscali (World Online) Denmark, we did prefix
filtering on our peers, the results of that can be seen on (Though that is old, january this
I believe that TeleDanmark also still do IRR filtering, and I know of
several providers in Denmark who are ready to follow suit as soon as
some of the "worst IRR-offenders" have updated their IRR
records (which
actually has happened already)

If you decide to implement IRR filtering you may want to see how your
peers perform in the IRR area by using a small utility, which can be
downloaded from This is the utility that
was used to produce the stats for Tiscali's router.

Thanks. (Yes, successfully filtering peers wrt IRR sometimes require human
interaction - asking peer not up-to-date to become so.)