> Small (say, under 50,000 customer) ISPs in my experience have a planning > horizon which is less than five years from now. Anything further out than > that is not "foreseeable" in the sense that I meant it. I have much less > first-hand experience with large, carrier-sized ISPs and what I have is a > decade old, so perhaps the small ISP experience is not universal, but I'd be > somewhat surprised giving the velocity of the target and what I perceive as > substantial inertia in carrier-sized ISPs whether there's much practical > difference. > Ready or not, IPv6-only (or reasonably IPv6-only) residential customers are less than 2 years out, so, well within your 5-year planning horizon, whether those ISPs see that or not. Denial is an impressive human phenomenon.
> So, what's a reasonable target for the next five years? > In five years we should be just about ready to start deprecating IPv4, if not already beginning to do so. > 1. Deployed dual-stack access which interact nicely with consumer CPEs and > electronics, the IPv4 side of the stack deployed through increased use of NAT > when ISPs run out of numbers. > Icky, but, probably necessary for some fraction of users. Ideally, we try to avoid these multi-NAT areas being done in such a way that the end user in question doesn't also have reasonably clean IPv6 connectivity. > 2. IPv6-only access, CPE and hosts, with some kind of transition mechanism to > deliver v4-only content (from content providers and v4-only peers) to the > v6-only customers. > This is, IMHO, preferable to option 1. > Perhaps it's because I've never seen a NAT-PT replacement that was any > prettier than NAT-PT, but I don't see (2) being anything that a residential > customer would buy before 2016. Perhaps I'm wrong, but I don't hear a lot of > people shouting about their success. > Personally, I think DS-Lite is the cleanest solution, but, it isn't without its issues. The reality is that post-runout IPv4 is going to be ugly, regardless of whether it's NAT64 ugliness, LSN ugliness, or DS-LITE ugliness. IPv4 is all about which flavor of bitter you prefer at this point. The sweetness is all on IPv6. > Note, I'm not talking about the ISPs who have already invested time, capex > and opex in deploying dual-stack environments. I'm talking about what I see > as the majority of the problem space, namely ISPs who have not. > The majority of the problem space IMHO is end-user-space at ISPs that have put at least some dual-stack research effort in, but, haven't come to solutions for end-users. However, we're less than 2 years away from seeing what happens in those environments without IPv4. Owen
