IPv6 may already be irrelevant – but so is moving off IPv4, argues APNIC's chief scientist

There was always more pressing work to do than migrate, and CDNs have changed the rules

The chief scientist of the Asia Pacific Network Information Center has a theory about why the world hasn't moved to IPv6.

In a lengthy post to the center's blog, Geoff Huston recounts that the main reason for the development of IPv6 was a fear the world would run out of IP addresses, hampering the growth of the internet.

But IPv6 represented evolution – not revolution.

"The bottom line was that IPv6 did not offer any new functionality that was not already present in IPv4. It did not introduce any significant changes to the operation of IP. It was just IP, with larger addresses," Huston wrote.

IPv6's designers assumed that the protocol would take off because demand for IPv4 was soaring.

But in the years after IPv6 debuted, Huston observes, "There was no need to give the transition much thought." Internetworking wonks assumed applications, hosts, and networks would become dual stack and support IPv6 alongside IPv4, before phasing out the latter.

But then mobile internet usage exploded, and network operators had to scale to meet unprecedented demand created by devices like the iPhone.

"We could either concentrate our resources on meeting the incessant demands of scaling, or we could work on IPv6 deployment," Huston wrote.

Achieving scale rose to the top of to-do lists. Early mobile networks were built on IPv4, coupled with network address translation (NAT) to enable more devices to connect without requiring a unique IP address.

Not every NAT implementation was the same, but network operators learned to live with that. The advent of Transport Layer Security in web servers also helped to keep NAT viable.

Content providers, seeing the persistence of IPv4, didn't bother to adopt IPv6 – meaning network operators didn't need to, either.

Around 40 percent of the internet nonetheless came to support IPv6. Huston has previously told The Register a big reason for that is the small IPv4 allocations to China and India, where the old protocol just couldn't be reliably used to support their massive user populations.

But overall, he thinks it is time to stop suggesting that a successful transition from IPv4 to IPv6 means the older protocol has been eliminated.

"Perhaps we should take a more pragmatic approach and … consider it complete when IPv4 is no longer necessary. This would imply that when a service provider can operate a viable internet service using only IPv6 and having no supported IPv4 access mechanisms at all, then we would've completed this transition."

To reach that state, ISPs, connected edge networks and the hosts in those networks all need to support IPv6. So do all websites.

Say my name, say my name

But Huston contends that the advent of content delivery networks – which are the way the majority of content and services reach end-users – means there's no need to adopt IPv6.

CDNs, he argues, rely on domain names, not IP addresses. "It's the DNS that increasingly is used to steer users to the 'best' service delivery point for content or service. From this perspective addresses, IPv4 or IPv6, are not the critical resource for a service and its users. The 'currency' of this form of CDN network is names," Huston argues.

"The implication of these observations is that the transition to IPv6 is progressing very slowly not because this industry is chronically short-sighted," the APNIC scientist added. "There is something else going on here. IPv6 alone is not critical to a large set of end-user service delivery environments."

Indeed, he believes that we are already "pushing everything out of the network and over to applications."

"Transmission infrastructure is becoming an abundant commodity. Network sharing technology (multiplexing) is decreasingly relevant. We have so many network and computing resources that we no longer must bring consumers to service delivery points. Instead, we are bringing services towards consumers and using the content frameworks to replicate servers and services. With so much computing and storage, the application is becoming the service rather than just a window to a remotely operated service."

That trend means Huston wonders if networks will even matter in the future.

"The last couple of decades have seen us stripping out network-centric functionality and replacing this with an undistinguished commodity packet transport medium. It's fast and cheap, but it's up to applications to overlay this common basic service with its own requirements." The result is networks become "simple dumb pipes!"

Given that, Huston wonders if it's time to revisit the definition of the internet as networks that use a common shared transmission fabric, a common suite of protocols and a common protocol address pool.

Rather, he posits "Is today's network more like 'a disparate collection of services that share common referential mechanisms using a common namespace?'" ®