Yesterday I started developing the IPv6 section of my new DMVPN: New Features webinar (register here). I’ve been looking forward to this topic, wondering how they manage spokes having a mixture of IPv4 and IPv6 transport (public) addresses. Disappointment kicked in after a few minutes: they don’t. Even worse, the DMVPN for IPv6 feature allows you to run IPv6 over DMVPN tunnel, but not DMVPN between IPv6 endpoints.
I’m convinced Cisco implemented DMVPN for IPv6 to cater to the needs of those few huge multinational enterprises that have already rolled out IPv6 internally to get away from the RFC1918 subnetting mess (Bechtel is an oft quoted example). Most of us will face a different scenario in the near future: we won’t be able to get a public IPv4 address from our ISP (particularly in APNIC region, where the RIR exhaustion is predicted before the end of April 2011). Once we get there, we’ll be stuck and might have to fall back to point-to-point IPsec tunnels (those do work with IPv6).