That's assuming ULA would be the primary addressing scheme used. If that became the norm, I agree, the extra uniqueness would be desirable, perhaps to the point that you should be asking an authority for FC00::/8 space to be assigned. But then why wouldn't you just ask for a GUA at that point. You could still randomly get "0", and if you don't think people will keep cycling through random numbers until they get something pretty you're underestimating human will to control everything ;-) I see ULA falling into the role of things like embedded device management and sandbox networks, more than production, but who knows what will become "the way" to engineer the IPv6 network of the next decade. We've only applied ULA to things like web-based network registration and device management for devices that should never be accessed from off the network (but even there, we've been more in the mindset of using GUA with ACLs or null routes, etc to restrict access). It's really more of a utility address IMHO. On Thu, Oct 21, 2010 at 7:47 AM, Jeroen Massar <jeroen@unfix.org> wrote:
On 2010-10-21 13:33, Ray Soucy wrote: [..]
People may throw a fit at this, but as far as I'm concerned FD00::/8 will never leave the edge of our network (we null route ULA space before it can leak out, just like you would with RFC1918 space). So you can pretty much use it has you see fit. If you want to keep your ULA space short there is nothing stopping you from using something like FD00::1 as a valid address.
And then your company gets bought and you need to merge networks, that is: renumber as they picked the same prefix.
There is nothing wrong with RFC1918 per se, the big problem with it is that everybody else uses the same prefix, thus when you need to merge two networks you have collisions.
I at one time also though that 'merging networks' and 'renumbering' is easy, till I heard stories from folks who where doing that for really large networks, who basically told that they where introducing 7+ layers of NAT to solve that issue, as renumbering is simply not doable if you have a global organization and if you are merging things like banks, for some magic reason they want to be able to talk to eachother.
That is why there is ULA: low chance of collisions if one wants to stay in the RFC1918 mindset.
And if you want a guarantee of no collisions: go to your favorite RIR and get a prefix from them.
Greets, Jeroen
-- Ray Soucy Epic Communications Specialist Phone: +1 (207) 561-3526 Networkmaine, a Unit of the University of Maine System http://www.networkmaine.net/