[138578] in North American Network Operators' Group
Re: Internet Edge Router replacement - IPv6 route table
daemon@ATHENA.MIT.EDU (Owen DeLong)
Thu Mar 10 18:07:48 2011
From: Owen DeLong <owen@delong.com>
In-Reply-To: <4D793C22.7060104@ispn.net>
Date: Thu, 10 Mar 2011 14:58:55 -0800
To: Blake Hudson <blake@ispn.net>
Cc: "'nanog@nanog.org'" <nanog@nanog.org>
Errors-To: nanog-bounces+nanog.discuss=bloom-picayune.mit.edu@nanog.org
On Mar 10, 2011, at 1:01 PM, Blake Hudson wrote:
>=20
>> My concern is trying to find a router (within our budget) that has =
room for growth in the IPv6 routing space. When compared to the live =
table sizes that the CIDR report and routeviews show, some can't handle =
current routing tables, let alone years of growth. BGP tweaks may keep =
us going but I can't see how 16k or fewer IPv6 routes on a router is =
going to be viable a few years from now.
>>=20
>> Thank you,
>> Chris Enger
>>=20
>=20
> Does anyone think that the IP6 routes will grow like IP4 routes have?
> With most organizations being granted IP6 /32's - e.g. something =
larger
> than they could ever use - wouldn't you expect the number of routes =
to
> be much much fewer than with today's IP4 setup where even small
> organizations often have multiple routes, and big organizations may =
have
> hundreds?
>=20
Most end user organizations should be receiving a /48 per end site.
Most ISPs should probably get something larger than a /32 unless they
have fewer than 48,000 customers or so.
The number of prefixes per ASN in IPv6 should probably end up around =
1.75.
The current average in IPv4 is approximately 10.
> When sizing routers, shouldn't we be looking at the number of expected
> ISPs (AS's) active on the Internet, within the anticipated lifetime of
> the router? If so, then the question becomes how many is that - 16k
> seems very shortsighted, 128k maybe overkill (at least, for now). =
We're
> currently at 37k AS's (http://www.cidr-report.org/as2.0/). So 64k IP6
> routes would probably be the minimum that I would accept on a new =
single
> homed router. If I expected to act as a carrier, or participate in =
equal
> cost BGP routing on a multi-homed router, I'd need more.
>=20
16k is extraordinarily short-sighted. It will be at least 30,000 just to
duplicate the current IPv4 network. 128k is probably reasonable
headroom. I wouldn't want to go any smaller, given the likelihood
of some multiple slightly greater than 1 prefix per AS.
> As IP6 adoption grows, and networks start to de-aggregate, 128K IP6
> routes sound like a better number for the second or third revision of
> "IP6 ready" gear that would be purchased in 5+ years.
>=20
I would say 128k is more like the minimum for anything I would buy
now.
Owen
