On Wed, Jul 15, 2015 at 2:11 PM, Doug Barton <dougb@dougbarton.us> wrote:
On 7/15/15 8:20 AM, George Metz wrote:
Snip!
Also, as Owen pointed out, the original concept for IPv6 networking was a 64 bit address space all along. The "extra" (or some would say, "wasted") 64 bits were tacked on later.
Still oodles of addresses, but worth
noting and is probably one reason why some of the "conservationists" react the way they do.
It's easy to look at the mandatory /64 limit and say "See, the address space is cut in half to start with!" but it's not accurate. Depending on who's using it a single /64 could have thousands of devices, up to the limit of the broadcast domain on the network gear. At minimum even for a home user you're going to get "several" devices.
Allow me to rephrase: "A single /32 could have thousands of devices, up to the limit of a 10/8 NATted behind it". This, plus the fact that it WAS originally 64-bit and was expanded to include RA/SLAAC, is why I chose that analogy.
Next, let's look at the wildest dreams aspect. The current
"implementation" I'm thinking of in modern pop culture is Big Hero 6 (the movie, not the comics as I've never read them). Specifically, Hiro's "microbots". Each one needs an address to be able to communicate with the controller device. Even with the numbers of them, can probably be handled with a /64, but you'd also probably want them in separate "buckets" if you're doing separated tasks. Even so, a /48 could EASILY handle it.
Right, 65k /64s in a /48.
Now make them the size of a large-ish molecule. Or atom. Or protons.
Nanotech or femtotech that's advanced enough gets into Clarke's Law - any sufficiently advanced technology is indistinguishable from magic - but in order to do that they need to communicate. If you think that won't be possible in the next 30 years, you probably haven't been paying attention.
I do see that as a possibility, however in this world that you're positing, how many of those molecules need to talk to the big-I Internet? Certainly they need to communicate internally, but do they need routable space? Also, stay tuned for some math homework. :)
So, you're advising that all these trillions of nanites should, what, use NAT? Unroutable IP space of another kind? Why would we do that when we've already got virtually unlimited v6 address space? See what I mean? Personally I'd suspect something involving quantum states would be more likely for information passage, but who knows what the end result is?
I wrote my email as a way of pointing out that maybe the concerns (on
both sides)- aren't baseless,
Please note that I try very hard not to dismiss anyone's concerns as baseless, whether I agree with them or not. As I mentioned in my previous message, I believe I have a pretty good understanding of how the "IPv6 conservationists" think. My concern however is that while their concerns have a basis, their premise is wrong.
I wasn't intending yourself as the recipient keep in mind. However, IS their premise wrong? Is prudence looking at incomprehensible numbers and saying "we're so unlikely to run out that it just doesn't matter" or is prudence "Well, we have no idea what's coming, so let's be a little less wild-haired in the early periods"? The theory being it's a lot harder to take away that /48 30 years from now than it is to just assign the rest of it to go along with the /56 (or /52 or whatever) if it turns out they're needed. I personally like your idea of reserving the /48 and issuing the /56.
So you asked an interesting question about whether or not we NEED to give everyone a /48. Based on the math, I think the more interesting question is, what reason is there NOT to give everyone a /48? You want to future proof it to 20 billion people? Ok, that's 1,600+ /48s per person. You want to future proof it more to 25% sparse allocation? Ok, that's 400+ /48s per person (at 20 billion people).
At those levels even if you gave every person's every device a /48, we're still not going to run out, in the first 1/8 of the available space.
Split the difference, go with a /52
That's not splitting the difference. :) A /56 is half way between a /48 and a /64. That's 256 /64s, for those keeping score at home.
It's splitting the difference between a /56 and a /48. I can't imagine short of the Nanotech Revolution that anyone really needs eight thousand separate networks, and even then... Besides, I recall someone at some point being grumpy about oddly numbered masks, and a /51 is probably going to trip that. :) I think folks are missing the point in part of the conservationists, and all the math in the world isn't going to change that. While the... let's call them IPv6 Libertines... are arguing that there's no mathematically foreseeable way we're going to run out of addresses even at /48s for the proverbial soda cans, the conservationists are going, "Yes, you do math wonderfully. Meantime is it REALLY causing anguish for someone to only get 256 (or 1024, or 4096) networks as opposed to 65,536 of them? If not, why not go with the smaller one? It bulletproofs us against the unforeseen to an extent." As an aside, someone else has stated that for one reason or another IPv6 is unlikely to last more than a couple of decades, and so even if something crazy happened to deplete it, the replacement would be in place anyhow before it could. I would like to ask what about the last 20 years of IPv6 adoption in the face of v4 exhaustion inspires someone to believe that just because it's better that people will be willing to make the change over?