Subnet a /64 into /96

  • I've a pfsense 2.1 with ipv6 running on it with 4 interfaces :
    Wan,lan, dmz and wifi .

    I've setted up a tunnel using the pfsense documentation and services.
    All is running well until I decided to devide the /64 into /96 by interfaces.

    I've setted up 3 different ipv6 addresses on the interfaces, splitting the /64 into 3 /96
    I've setted up dhcpV6 server on the 3 interfaces.

    My computer still receive a /64 ipv6 instead of a /96 as configured on the firewall ip adress , and shown in the dhcpv6 config page.

  • Request a /48 allocation from

    Although not impossible i can not remember off hand if the differing sizes work. You will require that everything supports dhcp6 or static addressing. Autoconfiguration will not be possible.

  • Different sizing definitely works as long as everything is setup pretty static.

    They recommendation is that a /64 is used as a subnet, and if you want multiple subnets you ask for a /48. /96's still provide a huge amount of scope, but this won't have been tested nearly as well as using /64's. (so may your life be an interesting one…)

  • Just to make this clear, you can do this, but you will lose SLAAC. And thus computers will no longer auto configure a IPv6 address.

    Ofcourse setting up RA combined with a DHCP6 server will make this work, provided that all clients support static addressing (yes) or DHCP6 (no).

    Don't expect your phone to whizz into IPv6 action.

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