Is there hope for IPv6?
This article completely fails to mention that IPv6 is not just an extension of the address space but a whole different worldview about how to run a network:<p>- IPv6-to-IPv6 NAT has only been accepted very recently and very begrudgingly. Whatever your views are on NAT, the fact is that lots of people have network designs that rely on it, and if you want them to stop, you&#x27;re now asking them to couple two major transitions, which is a significant economic cost. (Option 3 in this article is IPv6-to-IPv4 NAT, assuming that the public internet will indefinitely be IPv4; it&#x27;s noteworthy that none of their options ever envision the public internet becoming IPv6.)<p>- IPv6 recommends the use of its own scheme, SLAAC, for address assignment, with DHCPv6 being also very recent and poorly implemented - for instance, Android has no DHCPv6 support and plans to never implement it <a href="https:&#x2F;&#x2F;code.google.com&#x2F;p&#x2F;android&#x2F;issues&#x2F;detail?id=32621" rel="nofollow">https:&#x2F;&#x2F;code.google.com&#x2F;p&#x2F;android&#x2F;issues&#x2F;detail?id=32621</a> . There&#x27;s also a &quot;stateless DHCPv6&quot; for communicating DNS servers but using SLAAC for addressing; without it, SLAAC expects you to use a scheme called RDNSS to communicate your DNS servers, which is also not 100% supported. So you now need to spend engineering time supporting all of these options because some devices only support one and some only support the other, and you need to come up with network designs that work with both SLAAC (which has strong opinions on how you use &#x2F;64s) and DHCPv6 (which doesn&#x27;t).<p>- IPv6 doesn&#x27;t use ARP, on the grounds that it&#x27;s a layering violation, a separate layer-3 protocol that runs directly on top of Ethernet but talks about IP addresses. Instead, IPv6 has a clever scheme for using multicast to transfer the information that ARP would convey, by having machines join multicast groups based on their MAC address. This works very, very poorly with networks that aren&#x27;t designed to support significant multicast load - for instance an attempted deployment of IPv6 caused packet storms in the MIT Computer Science and AI Lab&#x27;s network for about a week because their switches were falling back from multicast to broadcast: <a href="https:&#x2F;&#x2F;blog.bimajority.org&#x2F;2014&#x2F;09&#x2F;05&#x2F;the-network-nightmare-that-ate-my-week&#x2F;" rel="nofollow">https:&#x2F;&#x2F;blog.bimajority.org&#x2F;2014&#x2F;09&#x2F;05&#x2F;the-network-nightmare...</a> So a working IPv6 deployment involves upgrading all of your hardware to hardware that has good support for multicast, which is also a significant economic cost.<p>- Various protocols like Teredo and ISATAP attempt to set up tunneled IPv6 routing in preference to IPv4 routing, making it hard to do a staged deployment, especially if you have BYOD on your network. For bonus points, because they&#x27;re tunneled, you get different <i>and possibly worse</i> routes over IPv6, making debugging harder. So that&#x27;s a cost in additional L1 and L2 support.<p>If someone had come up with an IPv7 that&#x27;s just &quot;We extended IPv4 to 128-bit addresses and we left ARP and DHCP and NAT and everything alone,&quot; people would have switched to it already. But the powers that be are drowning in the second-system effect and nobody wants all the features they added.