North American Network Operators Group

Date Prev | Date Next | Date Index | Thread Index | Author Index | Historical

Re: who gets a /32 [Re: IPV6 renumbering painless?]

  • From: Stephen Sprunk
  • Date: Fri Nov 19 12:07:49 2004

Thus spake "Iljitsch van Beijnum" <>
On 18-nov-04, at 18:02, Jeroen Massar wrote:
Larger enterprises probably consist of 200 'sites' already, eg seperate
offices, locations etc. Thus they can, after becoming a LIR and getting
an ASN, which most of the time they already have, easily get a /32.
Jeroen, this is nonsense and you know it.

We've been discussing the big enterprise problem in multi6 (multihoming in ipv6) circles very extensively. At some point, I realized that the "I'm so huge I need private space" claim is false in 99% of all cases, as these organizations tend to have multiple sites (as you indicate above) but they generally do not have real connectivity between those sites. This means a single large prefix won't do them much good, and basically they're no different than a bunch of smaller single-site organizations.
Don't have "real connectivity"? I've personally worked with dozens of Fortune 500 companies that have internal FR/ATM networks that dwarf AT&T, UUnet, etc. in the number of sites connected. Thousands of sites is common, and tens of thousands of sites in some cases. Do you not consider these networks "real" because each site may only have a 16k PVC to talk to corporate?

However, since the _vast_ majority of communication is internal and all but a dozen hosts are hidden behind a NAT, nobody on the public Internet has any clue these networks exist. Even 10/8 is barely big enough to hold the largest of these, and in one case we had to use multiple instances of 10/8 with separate servers in each instance to allow for growth in the number of hosts at each site (or sites themselves) and handle protocols which were not compatible with NAT.

ULAs are one way to solve these sorts of problems (and many others), and PI space is another. Guess which one companies would prefer, given the cost and paperwork levels involved with each and the lack of any need for external communication?

Now I hate to be the bearer of bad news, but having unaggregatable globally routable address space just doesn't scale and there are no routing tricks that can make it scale, whatever you put in the IP version bits, so learn to love renumbering. And again, IPv6+NAT makes no sense as NAT works much better with IPv4 and with NAT you don't really need the larger address space.
If I have a disconnected network, why would I use NATs or be forced to renumber periodically? Why should disconnected networks use global addresses (and pay rent to the RIRs) in the first place?

ULAs are not about enabling NAT in IPv6.


Stephen Sprunk "God does not play dice." --Albert Einstein
CCIE #3723 "God is an inveterate gambler, and He throws the
K5SSS dice at every possible opportunity." --Stephen Hawking