website/docs: IPv6

website/docs/source/v2/networking/private_network.html.md

@@ -74,6 +74,35 @@ reachable.
 </p>
 </div>
 
+## IPv6
+
+You can specify a static IP via IPv6. DHCP for IPv6 is not supported.
+To use IPv6, just specify an IPv6 address as the IP:
+
+```ruby
+Vagrant.configure("2") do |config|
+  config.vm.network "private_network", ip: "fde4:8dba:82e1::c4"
+end
+```
+
+This will assign that IP to the machine. The entire `/64` subnet will
+be reserved. Please make sure to use the reserved local addresses approved
+for IPv6.
+
+You can also modify the prefix length by changing the `netmask` option
+(defaults to 64):
+
+```ruby
+Vagrant.configure("2") do |config|
+  config.vm.network "private_network",
+    ip: "fde4:8dba:82e1::c4",
+    netmask: "96"
+end
+```
+
+IPv6 supports for private networks was added in Vagrant 1.7.5 and may
+not work with every provider.
+
 ## Disable Auto-Configuration
 
 If you want to manually configure the network interface yourself, you