This wiki provides an overview of IPv6 for the Gandi Hosting platform.

Internet Protocol version 6 is the next generation protocol to be used for communication between devices on the internet. Due to the impending depletion of available IPv4 address space, IPv6 allows for more hierarchical and nearly inexhaustible number of IP addresses to be assigned to devices.

It got lost in the bit-bucket (there is no IPv5) ;)

In most cases, configuration of IPv6 on your server should be automatic. We use stateless autoconfiguration for IPv6, as outlined in RFC4862, on the Gandi hosting platform. As long as IPv6 is enabled on your server, it will acquire an IP address automatically. This IP address will be derived from the network prefix on the hosting LAN, as well the MAC address of your server's network interface. The MAC address is provided by the server provisioning system and will not change, even if your server is migrated to another physical host node.

If IPv6 is enabled for the server, when you perform an 'ifconfig -a' on the server you should see a link-local IPv6 address on every interface. This link-local address is used as part of the IPv6 Neighbor Discovery protocol (roughly the IPv6 equivalent to ARP in IPv4, but more robust and more feature-rich). A link-local IP address will resemble something like this in the output of 'ifconfig -a':

inet6 addr: fe80::222:15ff:fed7:d0dd/64 Scope:Link

If you do not see an IPv6 link-local address on your interface, then it means that the kernel is not enabled for IPv6, either because it is an older kernel without IPv6 support, or because the IPv6 module for the running kernel is not loaded. Modern distributions, however, should have the IPv6 module loaded automatically.

Detailed Specifications on how it relates to Gandi Hosting in Expert Mode can be found on the dedicated wiki page.