Editors' note on Thursday, September 24, 2015: The American Registry for Internet Numbers announced today that it had given out the last of the IPv4 addresses it had in its free pool for North America. The article below is from 2011 and provides backstory on what that means. *

The internet has run out of room.

Like a prairie with no more vacant land to homestead or a hip area code with no more cellphone numbers, the pool of available numeric internet addresses has been completely allocated as of Thursday (.pdf).

With that, the frontier has closed. The internet – in its current form – is now completely colonized. All that's left is to divide the allocated properties into ever-smaller portions, or to start trading what's already been assigned.

This change will have no immediate effect on ordinary people, but will eventually force any company that wants to be on the internet to reckon with a complicated and potentially expensive technology transition.

It could also introduce widespread delays and other strange behavior into the internet at large.

>'It'll be harder to do things that used to be easy.'

"In a sense the net's going to get stickier," says John Heidemann, a computer scientist at the University of Southern California who has done a survey of the distribution of internet addresses (shown above). "It'll be harder to do things that used to be easy."

The shortage of addresses could eventually slow down your favorite web services, make it harder for websites to verify your identity, and complicate the design of services that depend on computer-to-computer connections, like peer-to-peer file sharing, Skype and more.

The change is going to happen gradually, over a period of years, but it will happen, say experts who have studied the problem, and it starts today.

"This is 100 percent a real issue," says Martin J. Levy, director of IPv6 strategy at Hurricane Electric, a provider of high-bandwidth data and collocation services that has been predicting the exhaustion of addresses for some time now. "We are dealing with a finite resource. We are going to run out. And we are going to have build a new system that gets around that issue."

"It's not really a shortage so much as exhaustion. It's gone," Kumar Reddy, a director of technical marketing at Cisco, says about the address space.

How Things Work Now ——————-

The data-delivery scheme used by the vast majority of the net, known as Internet Protocol version 4, uses a series of four numbers (each ranging from 0 to 255) to uniquely identify every machine that's directly connected to the internet. That gives a total of about 4 billion possible IP addresses. These numbers, such as 63.84.95.56, underlie the more user-friendly domain name system, which uses URLs like stag4.wired.com.

IP addresses are like telephone digits, in that there's a finite number of them. Unlike the telephone system, however, there's no equivalent to the 718 or 346 area codes to expand to when Manhattan's 212 is full. It's as if every possible area code from 001 to 999 had already been utilized or reserved.

In some cases those "area codes" are full of paying customers. In other cases the numbers are simply being held for future use or reserved for technical reasons. But the bottom line is no new addresses are available.

It will take a while for the effects to trickle down to your level.

The organization responsible for allocating these numbers is the Internet Assigned Numbers Authority, which delegates blocks of IP addresses to five regional registries. It is IANA that allocated its last available IP address blocks to the regional authorities on Thursday.

The regional registries, in turn, allocate their IP addresses to companies, ISPs and telcos. With no new blocks coming from IANA, they will start to run out of their address pools over the next several years, starting with the Asia-Pacific authority, known as APNIC, probably in mid-2011.

As regional authorities run out of available IP addresses, their clients will too. That means ISPs and companies will have difficulty assigning unique IP addresses to their customers, employees and servers as soon as this year, starting in Asia.

When that happens, those companies have a choice. They can switch to the next generation of the Internet Protocol, known as IPv6, which has 2128 available addresses. That's enough to give 285×1028 addresses to every human being on Earth – no danger of running out of addresses there.

The Problem With the Solution —————————–

But many popular sites, such as Wired's website, don't yet have IPv6 capability. In fact, less than 0.25 percent of the internet is wired to work with IPv6, which means that if you're using IPv6, there's not a lot of web content to browse.

Supporting IPv6 also means buying or upgrading network equipment, an expense most companies will want to avoid as long as possible.

So even though your computer probably supports IPv6, your iPhone supports it, and your ISP may even offer IPv6 service, it's of no use to you unless each machine between your computer and the server that you want to reach is also using IPv6.

"There's a lot of good stuff going on in this space, but it isn't quite complete yet," says Levy.

Workarounds ———–

The alternative for companies is to implement workarounds, like network address translation (NAT), which lets multiple people or computers share the same IP address. It's a technique that your home Wi-Fi router probably uses already, and it works fine – except that it makes certain kinds of computer-to-computer connections more difficult.

>'You can't just rip and replace. You have to maintain some of that legacy connectivity.'

For instance, if you want to view a home webcam from your desktop at work, and you've got NAT at home, you can't simply use the camera's IP address. You need another system to coordinate the connection, and those additional systems add complexity.

There may be ways for companies to use the already-allocated addresses better. Heidemann surveyed all 3.5 billion allocated IP addresses, and got responses from only about 7.6 percent. Even accounting for technical difficulties or deliberately inaccessible sites, there are clearly a lot of unused addresses out there.

"There is some amount of headroom here. We can probably use the address space better," says Heidemann. "However, with that is going to come higher management overhead."

In addition to NAT, there are ways to translate IPv4 addresses to IPv6, helping to bridge the two kinds of networks. But eventually, everyone will be forced to adopt "dual-stack" solutions, where computers – from smartphones and PCs to web servers and e-mail servers – first attempt to connect using IPv6, then switch to IPv4 if that doesn't work.

"Everything you do, probably for the next two decades, will be dual-stack," says Joel Conover, senior manager for IPv6 at Cisco. "You can't just rip and replace. You have to maintain some of that legacy connectivity."

In other words, anyone with a network to manage will be facing a combination of NAT and IPv4-to-IPv6 translation issues, as well as the difficulty of managing dual-stack systems for some time to come. This will increase the complexity and cost of internet services, and there are bound to be some bumps along the way.

That's why, even though IPv6 has been available for about 10 years, it still hasn't been widely deployed. People are putting it off as long as they can. Now, with the pool of IPv4 addresses running out, the stalling tactics are finally going to stop working.

To help make the transition smoother, companies such as Google, Facebook and Cisco are planning to participate in "World IPv6 Day" later this year.

It's intended to be a chance for companies to set up and test IPv6-compatible systems, in the hopes that if they build the field, someone will come to play on it eventually.

"The companies that are going to be the most aggressive in implementing IPv6 are the ones that are the most-concerned about your experience on their website," says Conover.

Remember that the next time you have trouble connecting to your home-security webcam. It might just be the shortage of IP addresses that's at the root of your trouble.

See Also:- Google To Build Ultra-Fast, Consumer Broadband Networks in U.S.