IPv6 doesn't help in corporate environments, where it's often firewalled harder than IPv4. The fact that it doesn't support NAT is seen as a risk in such envir

IPv6 doesn't help in corporate environments, where it's often firewalled harder than IPv4. The fact that it doesn't support NAT is seen as a risk in such environments ( which rightly or wrongly consider it as a second level of firewalling ). Some deployments that I've seen use only site-scoped with no globally-routed prefixes. Everything Internetty has to go over IPv4, which makes the Security team's job easier; drop all IPv6 at the DMZ and drop all non-NAT IPv4.