[40945] in North American Network Operators' Group
RE: multi-homing fixes
daemon@ATHENA.MIT.EDU (Tony Hain)
Mon Aug 27 13:55:12 2001
Reply-To: <alh-ietf@tndh.net>
From: "Tony Hain" <alh-ietf@tndh.net>
To: <tme@21rst-century.com>, "Leo Bicknell" <bicknell@ufp.org>,
"Randy Bush" <randy@psg.com>,
"Daniel Golding" <dgolding@sockeye.com>, <nanog@merit.edu>
Date: Mon, 27 Aug 2001 10:54:02 -0700
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in line
> -----Original Message-----
> From: owner-nanog@merit.edu [mailto:owner-nanog@merit.edu]On Behalf Of
> Marshall Eubanks
> Sent: Saturday, August 25, 2001 2:31 PM
> To: Leo Bicknell; Randy Bush; Daniel Golding; Leo Bicknell;
> nanog@merit.edu
> Subject: Re: multi-homing fixes
>=20
>=20
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> >
> >On Fri, Aug 24, 2001 at 03:11:39PM -0700, Randy Bush wrote:
> >> please look at slides 11 and 15 of
> >>=20
> >> <http://psg.com/~randy/010809.ptomaine.pdf>
> >>=20
> >> the /24s of small multihomers is half the routing table=20
> (see geoff's data)
>=20
> >> and is growing radially (if you are silly enough not to=20
> filter that stuff).
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> >
> >Does anyone have a graph of the number of allocated AS numbers? I
> >ask because in a perfect world each AS would originate 1 prefix
> >only, as they got enough address space in their first alloaction
> >to service them forever. In that case growth of the AS table would
> >be the growth of the routing table.
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> There are a number of such plots - we have one at
> http://www.multicasttech.com/status/asn.plot.gif -=20
> see http://www.multicasttech.com/status/ for explanation -
> and there are ones at Telstra -see
> http://www.telstra.net/gih/papers/ipj/4-1-bgp.pdf and
> http://www.telstra.net/ops/bgp/pc3/bgp-as-count.html
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> By all indications, the growth in both active AS and BGP
> prefixes has slowed since the market collapse.
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> There are currently ~ 11,000 active AS and ~ 104,000 prefixes, so
> each ASN has on average about 9 and 1/2 prefix blocks.
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So by this indication multi-homing and exposing the prefix to the DFZ=20
is not the problem. The real problem is the inability to defragment=20
the prefix allocations. As Leo noted, if we could get to a single
prefix per AS we would stop having these discussions about table growth.
> Regards
> Marshall Eubanks
>=20
> >
> >The real world would never work like that of course, but it is an
> >absolute lower bound on the table size, I think. I do believe we
> >can get much closer to this world with address space sizes like
> >those available in IPv6, however it's not clear to me that people
> >are really trying to think that way.
> >
Historically this has been true, because there has been a disconnect
between the operational goal of minimizing the table size through=20
enforced aggregation, and the business goal of giving the customer
the provider independence they want. I welcome all comments on:
http://www.ietf.org/internet-drafts/draft-hain-ipv6-pi-addr-00.txt
http://www.ietf.org/internet-drafts/draft-hain-ipv6-pi-addr-use-00.txt
and their applicability here. I am planning on modifying the discussion
on aggregation to account for the business reality that all multi-homed
prefixes will show up in the DFZ, because there is no motivation to
aggregate. Given the AS table is ~ 1/10 the IPv4 prefix table, I believe
there will be no problem with routers keeping up for the foreseeable=20
future because the number of prefixes per AS will approach 1.
> >--=20
> >Leo Bicknell - bicknell@ufp.org
> >Systems Engineer - Internetworking Engineer - CCIE 3440
> >Read TMBG List - tmbg-list-request@tmbg.org, www.tmbg.org
> >
> >
>=20
> Marshall Eubanks
>=20
> tme@21rst-century.com
Tony
