John, mixed bag of nasties here. Routing, addressing, and (of course) the DNS. More fun than should be legal on a friday afternoon. Routing: there is a varient here. Think about routing table slots. If I get one, does it matter what the length of the prefix that I put in it? There are other abstraction methods besides aggregation, at least thats what some smart people are telling me. The other bits will have to wait. % * From an RIR, as PI space % % * From an ISP, as PD CIDR space. ISPs might sensibly % decide to charge less (in money or aggravation) for % space which no one intended to route. Or might not: the % marketplace is good at sorting out these things, as long % as the RIRs are willing to make allocations to ISPs that % reflect the desirability of having addresses for % isolated networks unique and reflecting the ISPs to % which they might ultimately connect. % % * From some other process, as long-prefix, almost % certainly unroutable, isolated space. This process % could presumably be designed to be very lightweight in % charges and administrative costs. % % So, while I'm very hesitant about anything that ties addressing % (of any sort) to DNS names, I'm not convinced that Dave's % suggestion is worth dismissing out of hand. % % Three additional observations: % % (i) Tony's response to my note seems, to me, to turn SL largely % into a policy problem, not a technical one. We haven't have % really good success binding policies into protocols. That % doesn't convince me that we should never do so, but it does seem % to argue for looking at alternatives, even radical ones. % % (ii) ISPs impose restrictions on their customers all the time % and often even enforce them. Many of us consider some of these % to be desirable (e.g., terms and conditions prohibiting % spamming) and others less so (e.g., prohibitions against running % server or peer-peer protocols over a cable network or address % restrictions that force reasonably-architected LANs into NAT % arrangements) but the conditions clearly exist. % % (iii) Yes, if I have an odd address and sufficient money, I can % almost certainly convince some ISP to route it. But that ISP's % leverage to get its peers to accept any long-prefix addresses it % happens to offer and route them may be distinctly limited, % especially if, by offering/announcing those addresses, it is % violating a well-understood policy against doing such things. % (For example, an RIR policy that made PI address allocations % much more difficult for ISPs who were guilty of routing table % pollution by short prefixes could really focus the attention.) % So it seems to me to be plausible to suggest that the right % place to prevent routing table explosion (or even "bloat") is in % routing decisions and acceptance of announcements, and not in % creating special address scopes. % % I also note that site local addresses open up a whole series of % questions about "locality" and scope-range. Perhaps we also % need "ISP-local" addresses (routing into one ISP's space, or % part of it, but not to that ISP's peers or transit customers) % and so on. The one thing that can be guaranteed about that sort % of arrangement is an extension of the "pay enough and someone % will route it" model will apply: If some ISP sees a potential % competitive advantage in offering such a product (and % addresses), the product will follow soon thereafter. And, % again, I think that this suggests that we had better figures out % how to deal with these things on a policy basis, not a % protocol-imbedded special address scope one. We are almost % certain to have the policy problem anyway and it is not clear % that special cases for peculiar address scopes will buy us that % much in addition. % % john % % -- --bill Opinions expressed may not even be mine by the time you read them, and certainly don't reflect those of any other entity (legal or otherwise).