IPv4 Runs Low Faster Than IPv6 Is Adopted

On the Seinfeld episode, "The Dealership," Kramer takes a test drive. The salesman asks about gas and Kramer responds, "There's still some overlap between the needle and the slash below the "E"...I've been in the slash many times. This is nothing. You'll get used to it."

According to engineers at Hurricane Electric and iNetcore, by mid September, 2011, the Internet registries are expected to run out of routable IP addresses to assign. We'll be approaching "the slash" soon enough as addresses for users, hosts and devices will suddenly become a scarce resource. While 2012 apocalyptic visions aren't expected, the problem remains serious. Migrating to IPv6 is the leading approach, with its much larger address space of a little more than 340 trillion addresses. IPv6 could also introduce a number of engineering headaches for enterprises and consumers.

During the early days of the Internet, publicly routable addresses were awarded liberally. As such, organizations involved in the building the Internet accumulated massive blocks of IPv4 addresses. MIT and IBM have some 16 million IPv4 addresses allocated to them. AT&T holds twice that many. Neither of those organizations are likely to run out of addresses any time soon. While everyone agrees that IPv6 may provide the long term answer, how to get to IPv6 is a different matter. Until that's worked out, a number of provisional approaches are being considered to ease the demand for IPv6.

There have been proposals to reclaim some of unused addresses and sell them on the open market. The registries who assign addresses to ISPs would manage this marketplace. Such an approach will only create more complexity and delay the inevitable by about a year, says Leo Vegoda, the number resources manager for ICANN, and the person responsible for looking after the IP address and autonomous system numbering spaces. Loosely defined, an autonomous system refers to a set of IP subnets and the organization that manages them, that collectively route to the Internet. Autonomous Systems (AS) are assigned Autonomous System Numbers (ASN).

Determining the addresses that can be reclaimed from an AS is no simple feat. "The fact that an address is not routed doesn't mean that it's not being used," Vegoda  says "Nor does it  mean that they are using the whole allocation.  It's just not clear."  However, in the bigger scheme  of things a reclaiming those addresses wouldn't help all that much "We allocate a /8 per month, roughly," says Vegoda, "Each /8 is 16 million addresses. If they could reclaim a half dozen or dozen /8s, that would only push out the issue by a year."The simplest approach to resolving the Internet addressing problems remains the least realistic one. Back in 1998, the IETF specified IPv6, the next generation IP addressing. There are a number of benefits to IPv6, but most significantly IPv6 uses 128-bit addressing for virtually unlimited number of addresses. IPv4 uses 32-bit addressing.

Since its introduction, IPv6 has slowly grown until about five years ago. Since 2004, the number of IPv6 announcements within the Internet's BGP routing tables has quintupled, rising from about 500 to 2500 announcements today. Today there are 1867 unique IPv6 Autonomous Systems (ASes), but only a small fraction offering transit between networks, according to Geoff Houston, chief scientist APNIC, responsible for assigning IP address blocks in the Asia Pacific region. Houston is also an adjunct research fellow at the Centre for Advanced Internet Research. The most interconnected IPv6 provider, Hurricane Electric, reaches 675 other ASes.

The lack of available IPv4 addresses makes demand for IPv6 strong amongst new, very large networks. For example, when Comcast wanted to access its 50 million set-top boxes, the cable provider assigned IPv6 addresses to each of them. Similar approaches are expected to work for sensor and other closed networks.

Despite having the largest population in the world, China, for example, only has 8.72 percent of all IP addresses. The same goes for Japan, who today has just 6.92 percent of all IPv4 addresses. The US today holds 42.57 percent of all IPv4 addresses. With so few available addresses, China and Japan are known to be major proponents of IPv6. China Telecom has 208 million broadband subscribers, still a fraction of the 1.3 billion people that make up  the country. Equipping all of those customers with IPv4 addresses today remains infeasible.

Wireless providers are also pushing towards IPv6. Consumer demand for faster connectivity is pushing service providers to accelerate their deployment of 4G technologies, and in particular, Long Term Evolution (LTE). LTE assumes that phones connecting to the network are IP devices. As such every phone on the LTE network will need an IP address. Projection on the exact number of cellular subscribers of LTE devices are all over the map. Infonetics Research expects that by 2011 there will be 5.2 billion cellular customer while TeleGeography puts that number closer to 2 billion in 2013. Regardless, even a fraction of either number will be enough to exhaust the IPv4 address space.Wireless carriers need IPv6 and are evaluating the technology closely. "We are fully IPv6 operational at this point," said an AT&T spokesperson contacted for this article. Verizon refused to comment for this story, but public reports indicate that the company is aggressively pursuing IPv6. Earlier this month, Verizon updated an RFI for a prototype LTE device that will use IPv6 for its IMS connectivity and dual IPv4/IPv6 access to the Internet, administration and Verizon own application networks.

In all of these instances, whether the service provider is interconnecting sensors,  set-top boxes, or mobile phones, the networks are functionally independent from the Internet. They provide a specific application that may not require content to attract users, as in the case of set-top boxes and sensor networks. Where Internet content is important, such as with China Telecom's network or the Verizon network, the sheer scale of the potential customer base should be enough to drive IPv6 adoption.