Phone numbers and analogies

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Our local area code (814) is running out of phone numbers. When discussing IPv6 with non-technical folks, I frequently use the hypothetical scenario of running out of phone numbers as an analogy for IPv4 address depletion. The conversation usually goes like this:

Imagine if we were running out of phone numbers. One way of solving that problem would be to make them bigger. Instead of ten digits, what if we made them thirty digits? If we did that, how many other things would we have to change? Some mundane things like business cards, letterhead, and phone books. But also more substantial things, like form processing software, backend provisioning software, and legal intercept software. All of that would take years to design, test, and deploy.

(By the way, we're not running out of phone numbers. The NANP projects that the US is fine through at least 2039.)

All analogies break down at a certain point. Technically, the phone number analogy isn't accurate, but it's a reasonable way to explain to my parents what I do at work. Technical details aside, there's (at least) one significant difference between running out of phone numbers and running out of IPv4 addresses: People don't deny that we'll run out of phone numbers.. As I said above, we're in no danger of doing so right now, but the day will come when our population will grow to a point that it will exhaust the telephone numbering plan. That day is far away, but when it comes, we'll have to start adding digits.

On the other hand, some people do deny that we're running out of IPv4 addresses. I don't understand this. The data is unequivocal: We are running out. Fortunately, over the past few years, the data became more clear, and most of the deniers have changed their opinions.

Still, we've never had people advocate for a telephone equivalent of NAT. We've never heard people claim that it's a security threat to have their phone "exposed to the public telephone network." When ten-digit-dialing was introduced years ago, some people complained about the hassle, but speed dial and phone address books solved that problem. When it's noticed at all, ten-digit-dialing is seen as a technological impact of population growth, whereas IPv6 is often seen as some sort of personal assault on the sysadmin asked to deploy it.

I am very concerned that the Internet community has waited too long to begin serious efforts for IPv6 deployment. Only 10% of the IPv4 address pool is left. It will probably be gone 2.5 years. Yet only 5% of the Internet supports IPv6 (as measured by BGP announcements). I just don't see a way to get from 5% to 100% before we run out of IPv4. The next few years will be interesting, to say the least.

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Matt Simmons said:

The telephone equivalent of NAT is a PBX with built-in extensions, but you're right in that no one is suggesting that PBXes will relieve the burden of upgrading the phone system at some point.

And people should be thankful. At least computers are intelligent enough to deal with the upgrade. Can you imagine upgrading the telephone system to hex?

Erik Kline said:

I think you make a very good point about people not denying that we'll run out of phone numbers. It's rather funny, actually. But I think it's borne from direct renumbering experiences. Most people I know have been affected by or witness to at least one if not two or three area code splits. I think it's this that gives people first hand experience with running out of phone numbers.

In contrast only a very small number of (likely highly technical) people pay for static IP addresses for their residence. The result is that it's basically expected that your IP address may change ("have you tried rebooting your DSL modem?"). Consequently, any efforts taken by ISPs to deal with shortages (like starting to address DSL modems from instead of a public block) go unnoticed, save a possible modem reboot. Most residential users haven't really had the experience or understood it to be what it was, so incredulity is only natural I guess.

On the 5% -> 100% IPv6 deployment: I don't think that's going to be required, but that's a much longer discussion.

What grade do we get at Penn State, Derek?

Derek Morr Author Profile Page said:


That's a little hard to answer. Should I evaluate PSU compared to our peers in I2, to our peers that have deployed v6, or compared to where I think we should be (given that the IPv4 pool will run out in a few years).

Roughly 10% of I2 has some sort of public-facing IPv6 presence; in that regard PSU is ahead of the curve. Of those that have begun deploying IPv6, we're probably ahead of the curve a bit (I'd give us a B).

Having said that, I think we're several years behind where we should be to be prepared for IPv4 depletion. Of course, so is everyone else. There are some promising internal discussions taking place, but I probably shouldn't comment on them (yet) in a public forum.

Greg Larry said:

I agree with the analogies, it's easier to understand for ordinary non-technical person to understand why IPv6 is needed.

Robert said:

Under IPv4 we have the old familiar unicast, broadcast and multicast addresses. In IPv6 we have unicast, multicast and anycast. With IPv6 the broadcast addresses are not used anymore, because they are replaced with multicast addressing. - Robert vigrx

Niclas said:

Hi Derek! As the IPv6-guru you seem to be, can you, and people (or at least network-experts) remember any IPv6-address? I think most of us can remember quite a lot of IPv4 adresses, but who can remember 1983:9bc7:2948:c398? And that's only half of it.. :)

Derek Morr Author Profile Page said:

That's what DNS is for.

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