Normally I write blog entries directly on wordpress.com but this one I am composing in a text file because I can’t get to wordpress.com right now, or indeed to most of the Internet. There is nothing wrong with my Internet connection apart from the fact that I have deliberately disabled IPv4 on my iMac in order to see what I can do using IPv6.
IP stands for Internet Protocol and the Internet has run on version 4 since the beginning. With its 32 bit identifiers IPv4 has the capability to provide approximately 4.3 billion addresses. During the early days of the Internet it was hard to imagine running out of addresses but top-level exhaustion occurred in 2011 and the remaining address pools are expected to deplete within a few years.
By 1992 work had already started on a new version of the protocol and this time they were taking no chances. By 1996 IPv6 had been defined, providing approximately 3.4 x 1038 addresses by virtue of its 128 bit identifiers. Not only does IPv6 provide an unimaginable number of addresses but it also solves a lot of problems that were not considered when IPv4 was conceived. Nevertheless, deployment has been slow and by February this year the proportion of users reaching Google services over IPv6 only just reached 3 percent.
Being somewhat of a geek I have been looking forward to playing with IPv6 but that requires an IPv6 capable ISP and router. I had been getting online with BE since 2008 and although they provided a fast reliable connection with good customer support they did not seem to be in hurry to roll out IPv6. Last year when they were bought by BSkyB I started looking into alternatives and in February this year I migrated to Andrews & Arnold Ltd (AAISP), who I chose partly because they dig IPv6. I received a Technicolor TG582n router in the post and when my connection went down I switched routers and was soon back online. Visiting test-ipv6.com I now scored 10 out of 10 for IPv6 stability and
As soon as I thought I could connect to sites over IPv6 my natural reaction was to disable IPv4 and try things out. I am running OS X Mavericks and my iMac is still connected to my router using a good old fashioned Ethernet cable, so I just went into Network Preferences, selected Ethernet, and changed “Configure IPv4” from “Using DHCP” to “Off”. When I clicked “Apply” all IPv4 addresses vanished from the preference pane and under “Status” it said Ethernet was active with a long IPv6 address.
The first thing I did was try out a few major websites. I could still reach Google, Apple, Facebook and Wikipedia, but not WordPress.com, Twitter or Amazon. The sites I couldn’t reach gave a “can’t find the server” error, presumably because they do not have IPv6 DNS records. Obviously I could get to the AAISP website but I was pleased to be able to get to my own website (which I should have expected because I have a clueful hosting provider called Mythic Beasts). I use Mutt as my email client, which I have configured to send using msmtp via the AAISP outgoing server and fetch using IMAP tunnelled over ssh to my incoming server at Mythic Beasts. All of that continued to work just fine.
I then tried various Mac applications and was disappointed with the results. I can listen to songs in my iTunes Library but iTunes can’t sync or stream over the Internet and trying to go to the iTunes Store pops up an error which indicates that it thinks I have no network connection, while the App Store says “Cannot Connect to the App Store, An Internet connection is required”.
That is it for now. I will re-enable IPv4 so that I can post this blog entry. I also need IPv4 to print because my printer’s network card does not do IPv6 (as far as I can tell) and the router does not appear to be able to make its web interface available over IPv6. It was an interesting experiment but at present it is not realistic to run without IPv4 connectivity on a daily basis. Future tinkering will involve trying to connect in to my iMac over IPv6 from my Mythic Beasts shell account.