I have a network where ipv4 addresses are assigned via DHCP on the router.

The router, however, is capable of routing ipv6 but does not support ipv6 DHCP.

Would running 2 DHCP servers (one for ipv4 and one for ipv6) on separate machines (router + server) cause any issues?

  • 1
    Do you know you need DHCP for IPv6? Usually, your router will just advertise a subnet and your IPv6 machines will auto-configure. – heavyd Aug 29 '14 at 18:58

IPv4 and IPv6 are independent enough that the setup you describe should work just fine.

In fact you can even run IPv4 and IPv6 through two different ISPs. That would give some of the benefits from dual homing without needing to work with routing policies or BGP announcements.

But you don't need DHCPv6, if you only have a single network segment.

Your router can advertise itself with a /64 allocated for the LAN. That way SLAAC can be used to configure IPv6 addresses on the LAN without needing DHCPv6. This is AFAIK supported by more clients than DHCPv6 is.

The point where DHCPv6 gets interesting is how does the router know which /64 to advertise on the LAN. Your router could have a DHCPv6 client to request a prefix from a DHCPv6 server operated by the ISP. If DHCPv6 is not used for this, your router would need to be configured with a static IPv6 prefix.

  • I have a /64 block of IPv6 addresses HE tunnelbroker.net so I have a static prefix for the DHCP pool – arcyqwerty Aug 30 '14 at 18:55
  • @arcyqwerty HE by default allocate one /64 for the tunnel and one routed /64 for your LAN. You can allocate the routed /64 to your LAN and use SLAAC. No need for DHCPv6. SLAAC need a /64 in order to work, but it doesn't use all of the /64, so there is plenty of addresses left with which you can do DHCPv6. But why do you want DHCPv6? SLAAC supposedly works on more devices than DHCPv6. – kasperd Aug 30 '14 at 19:03
  • I was able to get things set up. It just seems like my router (MI424WR) doesn't like /64 prefixes... Thanks for help! – arcyqwerty Sep 1 '14 at 1:23

There should be no issues with this setup, since DHCP runs over IPv4 and DHCPv6 over IPv6. Since your router doesn't react to DHCPv6 messages, it is all right.

  • I think the router will route ipv6 messages and can have an ipv6 IP address, it just doesn't support distributing them – arcyqwerty Aug 30 '14 at 1:44
  • Yes, obviously the router will route IPv6 messages, but my message was about DHCPv6 messages and reacting to them. – Tero Kilkanen Aug 30 '14 at 10:05

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