route filtering policies (from "split b" thread)

[Hostmaster, Verant]

I understand what you are saying, and I could accept it and be on my way if
this was the consistent message from all.

But there are many major ISPs that will accept any /24 and shorter.  Why
some would filter and many others would not does not make sense.  The 78K
routes on my router take up 13MB of space.  

Again, I can understand filtering some of the older class A's and B's, where
it truley is a case of ISPs that lease pieces of their network space to
customers, and an aggregate route is usually all that's needed to get to
their customers efficiently.  But in the case of 24.*.*.* and 64.*.*.*,
where smaller blocks are given out.  I'm looking through my bgp tables, and
see hundreds of routes that are longer than /20 in both.

One question has still not been answered is - what is the smallest block of
64/8 that ARIN will assign?

But really my main point is - if many large ISPs are willing to simply
accept all /24 and shorter, why won't the others that are in the minority
follow suit?

----
Dani Roisman
Verant Interactive
hostmaster at verant.com
(310) 840-8753


> -----Original Message-----
> From:	cwinter at communicationnation.com
> [SMTP:cwinter at communicationnation.com]
> Sent:	Monday, June 05, 00 3:18 PM
> To:	Hostmaster, Verant; 'Paul A Vixie'
> Cc:	arin-discuss at arin.net; Brent Walters; Joe Murray
> Subject:	Re: route filtering policies (from "split b" thread) 
> 
> Dani,
> 
> At present there are about 40,000 some-odd CIDR routes being propagated.
> This takes just shy of 64meg. on a Cisco router - you can go to a publicly
> available route server to check this out - so we all order border routers
> with a minimum of 128 Meg. If no agriagation was done, it would be very
> easy
> to exceed the maximum available memory a Cisco router can handle - at
> present 256Meg. It does not take a lot of CPU to forward and receive route
> updates.
> 
> EBGP - Exterior BGP (vs. IntereiorBGP) does not like to announce subnetted
> /24 - thank goodness. Good policy is to aggrigate as much as possible, and
> this is the force driving Router Arbiter Data Bases. To try to keep the
> Internet from "flyingh apart" as one company put it.
> 
> A /20 is the smallest usuall allocation ARIN will make - there are a few
> exceptions ...
> 
> Charles Winter
> cwinter at communicationnation.com
> 
> 
> ----- Original Message -----
> From: Hostmaster, Verant <hostmaster at verant.com>
> To: 'Paul A Vixie' <vixie at mibh.net>
> Cc: <arin-discuss at arin.net>
> Sent: Monday, June 05, 2000 2:30 PM
> Subject: RE: route filtering policies (from "split b" thread)
> 
> 
> > Our situation is that we are multihomed to a few providors at each
> location,
> > but not necessarily with a backbone-grade link between each physical
> > location.  We do not resell connectivity, but use it all for our own
> > Internet application serving.
> >
> > So it's not really that irresponsible, in that we cannot just take
> blocks
> > from our providers.  I know of providers that accept as small as /24s,
> and
> I
> > know of networks that announce /23s and /24s and have no aggregate to
> fall
> > back on.  In fact in the case I described, we were able to affect a
> change,
> > which was prohibiting many cablemodem customers from accessing not only
> us,
> > but the network of a large ISP.
> >
> > But perhaps you can shed some light on the question asked by another on
> this
> > thread - why exactly would you filter on anything shorter than a /24?
> RAM
> > on your routers? CPU?  On my network, I want to pick up as specific
> routes
> > (well, up to /24) as the other network wants to announce to me - chances
> are
> > I'll get a better connection using a more specific prefix.
> >
> > Follow up question - where do you come up with /20 as the magic length
> for
> > class A's and B's, but /24 for class C's?
> >
> > Additionally, ARIN is now handing out 64.0.0.0/8 in smaller blocks.
> Perhaps
> > someone on this list can speak to the smallest block being handed out in
> > 64.0.0.0/8.
> >
> > ----
> > Dani Roisman
> > Verant Interactive
> > hostmaster at verant.com
> > (310) 840-8753
> >
> >
> > > -----Original Message-----
> > > From: Paul A Vixie [SMTP:vixie at mibh.net]
> > > Sent: Monday, June 05, 00 2:04 PM
> > > To: Hostmaster, Verant
> > > Cc: 'arin-discuss at arin.net'; Network Operations
> > > Subject: Re: route filtering policies (from "split b" thread)
> > >
> > > > Thanks for the URL... hm.. /20 and shorter only in 64/8?  That's a
> bit
> > > > strict, no?  We have different networks off our 64.34.128/18 block,
> > > which we
> > > > would like to announce in /21 and /22 blocks.  There's a good chance
> we
> > > > won't aggregate, since the networks might each have OC3 or OC12
> links
> to
> > > the
> > > > Internet, but in some places as slow as T1 between the two networks,
> and
> > > I
> > > > wouldn't want to backhaul accross the T1.
> > >
> > > that's an incredibly irresponsible way to build a net.  if you're
> going
> to
> > > be a transit aggregator, then by all means get small blocks your
> providers
> > > and pay them extra to get cutouts.  the expectation we all have when
> you
> > > get
> > > an address block is that you intend to advertise it, not carve it up.
> > >
> > > > Who should I contact at Verio to discuss losening the filtering
> policy?
> > >
> > > won't help.  see http://www.mibh.net/mibh-peering.html and know that
> if
> > > you
> > > tried to get us to loosen it we would definitely not.  there are
> dozens
> if
> > > not hundreds of nets running with this policy.  the thing to change is
> > > your
> > > plan, not the commonly implemented route filtering policy of the whole
> > > 'net.