22,000 Users
Since I posted an item a couple of weeks ago on World IPv6 Day, there have been several discussions both internal and external that suggest I may not have been entirely clear on the potential effects, so I am going to try and cover a few of those here.
First of all, and perhaps most importantly, nobody is going to be turning off IPv4 on June 8th. The purpose of World IPv6 Day is to enable IPv6 access to websites, not to remove IPv4 access. This means adding an ‘AAAA’ (quad-A) record in the DNS to popular websites such as Google and Facebook. It should be noted that the JANET website has had both IPv4 and IPv6 access enabled for several years, so if you do not have problems accessing the JANET website, you should be fine on June 8th. If, however, you or some of your users do have problems reaching the JANET website, that is an indication you should investigate a bit further before next Wednesday (I’d like to claim that the reason this blog is only available on IPv4 is to ensure it is still reachable next Wednesday, but the truth is that I don’t manage the system!).
Some operating systems ship (or have shipped) with some IPv6 transition mechanisms like 6to4 and Teredo enabled by default and not explicitly ‘depreferred.’ If these systems do not have native IPv6 access, they could be trying to use transition relays elsewhere. Not only may those relays be slow to respond, access to them may be blocked by your firewall and the systems could take a long time to realise this and fall back to IPv4. Again, if you can reach the JANET website, you should be fine, but use one of the connectivity tests I mentioned in the previous blog, such as Test IPv6.
Here at JANET we received a concerning email from Google earlier in the week. It stated that some preliminary tests they have done suggest JANET is one of the top 10 networks worldwide for users that will have broken IPv6 access (access that will take longer than 15 seconds to fall back to IPv4), and they estimate there are 22,000 such users (Google also used a figure of 1.5% but admit the estimate could be very inaccurate) on JANET. Those 22,000 users are almost certain to mean helpdesk calls next Wednesday.
[Update: I have received some more data from Google on what is broken, by and large it appears to be users of Mac OS X earlier than 10.6.5. JANET(UK) will be contacting the few sites that are directly mentioned, but if you have Macs with anything other than Mac OS X 10.6.5, 10.6.6 or 10.6.7 on campus and cannot upgrade you may be best off either disabling IPv6 entirely or using recent versions of Chrome (11.0.696.71) which try IPv4 and IPv6 in parallel, specific details are on the ARIN wiki.]
I can only guess that this is due to the historically open nature of campus networks compared to regimented corporate networks that are strictly controlled by a central IT support function. If the 22,000 user figure is true, those users will be calling your helpdesks on Wednesday, so it is worth having some information ready, such as the IPv6 Test website, to diagnose the problems.
Some additional URLs that may be helpful are:
I’m suprised that there are so many people out there running OSX earlier than 10.6.5. The Apple OS automatic updates are fairly easy to run and are automatically set to get the latest releases. I’m sure it’s no bad thing if IPv6 World Day leads to support teams get all their Mac users patched to the latest version.
[...] might this affect you? It’s worth checking out Rob Evan’s blog for a view from the JANET ops perspective, which discusses the potential impact for JANET-connected [...]