>> AFAIK, you can't... MAC addresses are uniques numbers assigned to NICs at
>> time of production by the manufacturer. 
>> 
>> I can't see the point of wanting to change this, but you must have
>> your reasons... perhaps you can enlighten me on this one...
>
>Several "high-availability" systems use MAC address modification as part
>of their low level mechanism. It would be nice to have it available on
>NetBSD too.

	ther are a lot of complication around here:
	- we can control source MAC address for outbound packet for some cards,
	  but not for some other cards.
	- when we try to configure for "high-availability" for IPv4, we need
	  more clever ARP table (which maps peer's MAC address and the MAC
	  address we have used).
	- when we generate outgoing IP packets, we may need to configure
	  the same IP address onto two interfaces.  then, we have tricky
	  setup for interface route on routing table (which interface should
	  we point for 10.0.0.0/24?)
	- load balancing policy is of course more difficult than single
	  interface cases.
	- IPv6 link scope issues.
	- IPv4/v6 multicast group management - we use interface index
	  for management, so now we need to support mapping between
	  multiple interfaces and single multicast group.

	it seems to me it can best addressed by virtual interface that binds
	multiple ethernet interfaces into one (like vlan* interfaces), however,
	it still does not solve some of the above complications.

itojun