On Sat, Aug 6, 2011 at 5:21 AM, Owen DeLong <owen@delong.com> wrote:
At least don't make your life miserable by experimenting with too many different assignment sizes, or advocate /64s or something, that's considered a design fault which will come back to you some day. Read the RfCs and RIR policy discussions in the archives some years ago.
Note that in this thread, you advocate three things that are a little tough to make work together: * hierarchical addressing plan / routing * nibble-aligned addressing plan * minimum /48 per customer If I were, for example, a hosting company with IPv6 terminated at the layer-3 ToR switch, I would then use a /40 per rack of typical "dedicated servers." If you then want some bits to be a POP-locator field for your hierarchical routing scheme, you are already forced to request more than a /32. The number of customers per layer-3 device for typical end-user access networks was around the same into the late-1990s/early-2000s, as ISPs had racks of Portmasters or whatever box of choice for terminating dial-up. Densities have changed, but this doesn't necessarily win you an advantage when combining those three properties. This is especially true if you consider that density may change in a difficult-to-predict manner in the future -- a BRAS box with a couple thousand customers today might have three times as many in a couple of years (IPv6 is supposed to help us avoid renumbering or injecting additional routes into our network, right?) As an access provider, if I shared your view, I would be reserving a /36 or /32 per BRAS box. If I then want some additional bits for hierarchical routing ... I'm going to need a pretty large address block for perhaps a pretty small number of customers. After all, my scheme, applying your logic, dictates that I should use a /32 or perhaps a /28 per each POP or city (I need to plan for several BRAS each), even if I don't have a lot of customers today! I think /56 is more sensible than /48, given the above, for most end-users. Either way, the users will be gaining a lot more flexibility than they have with IPv4 today, where they probably get just one IP address and have to pay a fee for any extras. Giving the typical end-user 8 fewer bits worth of address space allows the ISP network more flexibility for hierarchical routing before they have to go to their RIR and figure out how to justify an out-sized allocation. Also, if folks would stop thinking that every subnet should be a /64, they will see that end-users, makers of set-top-gateways, or whatever, can certainly address a whole lot of devices in a whole lot of subnets even if the user is only given a /64. Do we think DHCPv6 won't be the most common way of assigning addresses on SOHO LANs, and that SLAAC will be essential? I, for one, think that some ISPs will be sick and twisted enough to hand out /128s so they can continue charging for more IP addresses; but certainly the makers of IPv6-enabled devices will foresee that end-user LANs might not be /64 and include the necessary functionality to work correctly with smaller subnets. Before you beat me to it, yes, we seem to have completely opposing views on this subject. I will change my mind when I can go to the RIR and get a IPv6 /24 for a small ISP with a few POPs and a few tens of thousands of customers. Should RIR policy permit that sort of thing? -- Jeff S Wheeler <jsw@inconcepts.biz> Sr Network Operator / Innovative Network Concepts