Iljitsch van Beijnum <iljitsch@xxxxxxxxx> wrote: > On 16 sep 2009, at 18:40, IETF Member Dave Aronson wrote: ... > What's the point of running IPv4 when you can do everything you need to do > over IPv6? (Note that it works the other way around, also...) Inertia. Lots of people are already running IPv4, with little to no incentive to switch their machines over. Even when they get a new one, IPv4 is what they're used to. As long as IPv4 is still supported, and especially when it's the default, IPv4 is what most people will use, both at home and in business. > IPX, DECnet, AppleTalk etc disappeared from view pretty quickly as IP > conquered the world. ...and provided incentive via connection to the rest of the world. In order to play on "teh Intarwebs", they had to speak IP... and once they're doing that, there's less incentive to keep running something else on internal nets. In order to be be connectable directly to the Internet, more and more machines started supporting IP. This made it easy to go IP internally as well, for those businesses (and the occasional home) that had an internal network. I don't see anywhere near as strong an incentive to go to 6. The average user, even the average business, does not care that the IPv4 address space is endangered... until of course it means that their IPv4 address is more expensive. Nor do they care about the added features; heck, they probably don't even *understand* most of the added features! > But before the bury IPv4, it would be a good signal to make IPv6 a full > standard. Agreed. That's *part* of what needs to happen, and in fact one of the first major pieces. Here's how I see it playing out (omitting further IPv4-supporting workarounds): - IETF declares IPv6 a full standard. - More ISPs start offering IPv6 to end-users (be they homes or businesses). Broadband ISPs can play a major role in this, by issuing cable/DSL/FIOS/whatever modems that support IPv6 (at least on the ISP side), and making that the default. IPv6 service *may* be cheaper than IPv4 at this point, due to larger address supply. (Anybody know about relative pricing now? I don't.) - Hardware and software makers offer more items supporting IPv6, and more fully (in the popular parts), due to customer demand. - Prices (hardware, software, and service) drop due to economy of scale, and competition. Soon, IPv6 should be at least not more expensive than IPv4. Eventually, it will probably be cheaper, though I'm having a hard time articulating why I think this is so certain. This will be the tipping point. - Businesses and homes start switching their ISP connection to IPv6. Due to economic incentive, this should happen fairly quickly after the previous item. - Businesses and homes start switching their *internal* networks to IPv6, due to not wanting to support multiple styles of IP. Some will stay with IPv4 and NAT, some will go to IPv6 but still use NAT, and some will use an external address per device. - Some ISPs stop offering IPv4. - IEFT declares IPv4 historic/obsolete/whatever. My point is, I don't think this point will come within the next "several" years, as the preceding items put together will take longer than that. - More ISPs stop offering IPv4. - More homes and businesses stop using IPv4 internally, though still probably not quite all. - US Government gets serious about requiring that products support IPv6. Maybe they'll also want stuff coded in Ada, too. ;-) -Dave -- Dave Aronson, software engineer or trainer for hire. Looking for job (or contract) in Washington DC area. See http://davearonson.com/ for resume & other info. _______________________________________________ Ietf@xxxxxxxx https://www.ietf.org/mailman/listinfo/ietf