Allocating fixed IPv6 addresses to hosts with multiple NICs

John.Gibbins at John.Gibbins at
Wed Jan 12 00:48:20 UTC 2011

Is anyone handing out fixed IPv6 addresses with ISC DHCP?

With IPv4 we hand out IP addresses based on MAC addresses ("hardware Ethernet" and "fixed-address" config entries).
With IPv6 we hand out IP addresses based on DUID ("host-identifier option dhcp6.client-id" and "fixed-address6" config entries).

Our problem is that the DUID is system specific and not NIC specific.  To uniquely specify a NIC, I need to specify both the DUID and the IAID, but I can't find any way of specifying an IAID.  This effectively makes DHCPv6 useless for us on systems with multiple NICs.

Is there a way of handing out different predefined IPv6 addresses to for different NICs on a host?

I'm hoping that I've missed something (obvious or otherwise).  If not, I'll need to investigate alternate implementations.

John Gibbins
IT Security Operations (and IPv6 Evangelist)
CSIRO Information Management & Technology (IM&T)
Phone: +61 2 6124 1419  | Fax: +61 2 6124 1414 | Mob: 0419 605 562
John.Gibbins at | 
PO BOX 225, Dickson  ACT 2602
Do not let what you cannot do interfere with what you can do - John Wooden

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