Re: all the mails on Filtering

[Harsha Narayan <hnarayan () cs ucsd edu>]

Hi,
  But it appears that there are many cases where customers prefer to take
a prefix from the ISP rather than an RIR even if it is a /19 or a /20 -
for example from the /11 of a big ISP, there are 50 /19s and /20s which
are multihoming assignments.

  I was told that this saves the cost of RIR membership for the customer.

  Moreover, how do we know the RIR makes multihoming assignments from a
separate /8 - atleast in the case of RIPE it does not I think (in the case
of APNIC it does). If we are of sure of this - i.e. that a multihoming
assignment from an RIR comes from a separate section of the address space
- we can't filter.

Harsha.
On Wed, 13 Nov 2002, Jared Mauch wrote:

>       If you're multihomed you can generally obtain provider indepdent
> space from your RIR.
>
>       Most people who do this filtering do it on the RIR boundaries
> for their minimum allocation.
>
>       If you are annoucing your provider assigned space
> as a /24, they tend to announce the (/14 - /rir-minimum)
> so your packets will follow the aggregate.  If they
> are not announcing their aggregate then you will have
> problems.  Most people in that case would blame
> the provider for not announcing their space.
>
>       - Jared
>
> On Wed, Nov 13, 2002 at 10:25:53AM -0800, Harsha Narayan wrote:
> > Hi,
> >
> >   So what happens to multihoming assignments made by the ISP? That means
> > the multihoming assignment can't be used as a backup. If the customer's
> > connection to the ISP which made the multihoming assignment gets lost,
> > then it can't use its multihoming assignments (say a /24) to get traffic
> > from some other ISP?!
> >
> > Thanks to all,
> > Harsha.
> >
> > On Wed, 13 Nov 2002, Buddy Bagga wrote:
> >
> > > Greets,
> > >
> > > Look at <http://www.nanog.org/filter.html>. If I remember correctly, Verio
> > > used to filter prefixes longer than /19s in classful A range. Apparently
> > > this isn't the case anymore. But it would be naive to think that ISP only
> > > filter prefixes longer than /24.
> > >
> > >   Cheers,
> > >
> > > On Wed, 13 Nov 2002, Harsha Narayan wrote:
> > >
> > > >    Are there some ISPs who filter prefixes longer than /19 or a /20?. I
> > > > thought they filtered only prefixes which are longer than /24?
> > >
> > > ~
> > > Buddy Bagga
> > > Genuity | BBN
>
> --
> Jared Mauch  | pgp key available via finger from jared () puck nether net
> clue++;      | http://puck.nether.net/~jared/  My statements are only mine.