IPv6 & IPv4 Will Co-Exist for a Long Time
The World IPv6 Launch is set for next week on June 6th. On that day, website operators around the world will switch on IPv6 connectivity and keep it on. The event is a follow up to World IPv6 Day in 2011 in which over 300 websites switched on IPv6 for the day to see what would happen.
VeriSign takes dual track model
VeriSign, operator of root DNS servers and the .com and .net registries, has a unique role to play when it comes to IPv6. VeriSign sees traffic coming in as DNS queries and as record updates for domains. While many World IPv6 Day participants switched IPv6 off after the event in 2011, VeriSign has maintained IPv6 service on their site over the past year.
In an interview with Enterprise Networking Planet.com, VeriSign CTO, Burt Kaliski noted that the company has two perspectives when it comes to IPv6. The first is as a service-provider infrastructure vendor for the Internet, as an enabler for others to connect over IPv6 DNS. The other is as an enterprise that needs to enable IPv6 for its own use. In both cases, VeriSign is taking a dual-stack transition model that supports both IPv6 and IPv4.
"We're tending to see a co-existence of IPv4 and IPv6 when registrations occur and when traffic comes in we'll often see both an IPv4 and an IPv6 request due to the propagation of the dual-stack," Kaliski said.
From a DNS perspective, IPv6 is registered as a "AAAA" record in a domain registry, in contrast IPv4 DNS is stored in an "A" record. VeriSign is now seeing more AAAA records in DNS. As measured by queries coming into VeriSign's DNS resolution systems, IPv6 traffic is gradually increasing in root server traffic, as well. There are 13 root DNS servers that power the Internet and VeriSign manages the core A and J servers.
"We've seen an increase in the past year or so in the percentage of traffic to the DNS root servers carried over IPv6 from somewhere around one percent to between three and four percent," Kaliski said. "That means of all the queries we receive on a daily basis about three times as many are carried over IPv6 than a year ago and that's an encouraging sign."
Growth in .com and .net IPv6 traffic muted
Growth in IPv6 DNS traffic is a leading indicator of IPv6 adoption. But, while DNS traffic over IPv6 has grown, that doesn't necessarily translate into a growth of IPv6 traffic for .com and .net top level domains.
"We're not seeing a significant increase in the percentage of transactions carried over IPv6 for .com and .net and it has been relatively flat over the last year," Kaliski said. "
The fact that IPv6 DNS query volume is growing while IPv6 domain traffic is flat is not a contradiction. Kaliski explained that DNS queries proceed with a certain logic from the resolution system and it would be natural to start with the root servers sending out IPv6 requests. Once a user gets get back an address for a name server than the user speaks to the name server over whatever version of IP that works for the user.
"The starting point demonstrates the availability of IPv6," Kaliski said.
The complexity of the Internet and DNS resolution means that there are actually at least four options by which traffic can be delivered. A DNS query today can come over IPv4 or IPv6 and the item being queried can be either an IPv4 or an IPv6 address.
June 6: IPv6's D-Day
While June 6 is being promoted as the launch day for IPv6, the reality of widespread IPv6 usage is somewhat different. The world launch day is not a cutoff point or a switch over from IPv4, it's merely an open declaration from website operators that they will run IPv6 on a daily basis.
As to whether there should have been some kind of arbitrary cutoff and switch over to IPv6 from IPv4, Kaliski's view is that it's not possible. He sees a gradual deployment and co-existence of IPv4 and IPv6 over a long span of time. As opposed the say the recent U.S. switchover from analog to digital TV signal broadcasts, IPv4 and IPv6 can co-exist and use the same connectivity. With digital and analog TV there was no way to sustain both systems simultaneously and that's why a formal switchover had to occur.
"There will probably be IPv4 traffic somewhere for a very long time," Kaliski said.