Brokenness refers to the situation whereby a website is made accessible in dual stack, meaning both IPv4 and IP6, using records referred to as A’s for IPv4 and quad A’s for IPv6. Some end-users can experience slower access to the website or in some rarer instances no access at all. Brokenness is mostly attributable to older versions of the Mac Os operating system. The brokenness issue has been very well described by Eric Vyncke in a posting on the Belgian IPv6 website and has been monitored by Tore Anderson from Norway who has been measuring the impact of dual stack on customer loss for more than a year and shows customer loss dropping considerably over the last twelve months.

When Google started to make some of their sites accessible in IPv6 a major concern was broken connections caused by ISP, CPE, firewall and OS issues. It was initially estimated to potentially affect around 0.5% of end-users which is obviously unacceptable for any major search and web browsing site.

The issue has been gaining in importance as the remaining IANA IPv4 address reservoir could be empty as early as February 2011 according to some experts speaking at last week’s ARIN meeting. Google’s Lorenzo Colliti provided some edifying updates [PDF] on Google’s IPv6 deployment and the brokenness issue. Breakage for all clients was estimated at 0.082% and for white listed ISP’s 0.014% excluding Mac OS X numbers are in the ’ four nine’s territory’.

The need to increase rapidly the amount of IPv6 accessible content is clearly a rapidly growing priority. Google, Limelight, Akamai where quite adamant restating their commitment to have content and hosted content IPv6 accessible. In the meantime, Eric Vynckes’ compilation of IPv6 accessible website sites worldwide based on extraction of the top 50 websites per Top-Level Domain (TLD) from the Alexa list will help us us keep track of progress.

By the time ARIN meets next in April 2011, we might be able to offer a toast to the last free slash eight IANA could just have allocated and the Regional Internet Registry who got that last specimen.