I already covered that in a previous post, I would like now to share what happened to one of the webapp managed by Zaltana. That application is available through IPv4 and IPv6, and in despite of my intial thoughs, is accessed by a few people in IPv6 (this explains the need of this post). Moreover, these users are not aware of IPv6, they are not geeks, they are regular subscribers of the French Free ISP which provides IPv6 connectivity to its customers (without being aware of it, they are early-adopters of this new version of the IP protocol).

A few weeks ago, the IPv6 connectivity went down. And some users discovered some issues in accessing the website. This is due to the fact that most modern browsers try to connect in IPv6 when 1) there is an IPv6 connectivy (on the client side) and 2) the requested website has a domain name which can be resolved to an IPv6 address (e.g. AAAA record).

The issue came back to me and I directly contacted the support of the company providing the server (we only use dedicated servers from the two biggest French companies providing that kind of services in France)… and the problem was fixed… 4 days later! As a comparison, what happens if the IPv4 connectivy goes down? All lights turn red in the support engineers office and the problem is fixed within a couple of minutes.

This kind of issue has consequences:

  • on the service provider side (e.g. me in that case): suppose I want to provide IPv6 to test it. After such an issue, I simply remove the IPv6 connectivity. v4 is enough – note: I did not remove IPv6 as I am convinced we need it :-)
  • on the end-user side: even if most of the end-users don’t know IP at all, it has a bad impact. That’s why we see from time to time in forums folks saying to “disable IPv6″ to solve various issues (which have no relation with IPv6).

That’s why it’s good considering that if we want IPv6 to be adopted, it needs to work as IPv4, with the same quality. That’s the point of view of Google who provides IPv6 access to its services only to users from whitelisted networks (see http://www.google.com/intl/en/ipv6).