A bug in Windows 10 is undermining Microsoft's efforts to roll out an IPv6-only network at its Seattle headquarters.

According to Redmond's principal network engineer Marcus Keane, the software giant is struggling to move over to the decade-old networking technology due to a DHCPv6 bug in Windows 10, which made it "impossible" to expand its planned corporate network. "We have reported it to the product group, and they are duly working on a fix," he revealed today.

The horrible irony of Microsoft waiting on its own team to fix a networking bug aside, the post goes some way to highlighting why it is that IPv6 is still not widely available: because it's a mess.

First up, the existing routers at its Redmond offices didn't support RDNSS. Microsoft was using DHCPv6 to provide IPv6 addresses on its network, but Android doesn't support that.

"As we needed to support Android devices on our guest network, and Android doesn’t support DHCPv6, not having this feature was a problem," said Keane.

So the company went to the router manufacturer and asked them to add RDNSS, which Android can use. In the meantime, they shifted to a different set of routers for the IPv6-only network and used a VPN to connect to the larger network – something that Keane notes "isn't ideal."

Then they hit another Microsoft software problem: network authentication. Employees use the company's own Azure Active Directory cloud-based ID system to log in, but the dynamic system they use to achieve this is – you've guessed it – not supported over IPv6.

Again, Microsoft has gone directly to the vendor to include dynamic ACL-based authorization in its system. "We expect to complete testing of both the wireless controller code and the router code supporting RDNSS in the next month or so, meaning we should be able to roll out IPv6-only to the guest network in our Redmond campus in the next six months," Keane writes.

And once that happens, Keane predicts the real fun will begin: testing whether people's applications will work over IPv6. In the meantime, they're sticking with dual-stack.

You do have to wonder – if even Microsoft can't get IPv6-only working, what chance is there for any other company to? Can someone remind us again why the Internet Engineering Task Force decided not to make this next-gen networking protocol backward-compatible? ®