freebsd stable - Nov 2013 - how is the MAC for tap(4) computed?

There seems to be a very high rate of MAC address collisions when tap is
running on different machines.... is there anyway to make the selection of
MAC more random

In the last episode (Nov 04), Aryeh Friedman said:
> There seems to be a very high rate of MAC address collisions when tap is
> running on different machines....  is there anyway to make the selection
> of MAC more random
It looks like it's generated based on the number of ticks since boot, plus
the unit number of the tap device:

http://fxr.watson.org/fxr/source/net/if_tap.c#L434

So if you have devices created on boot on a bunch of machines, chances are
high that you'll get conflicts.  Maybe instead of using the 'ticks'
value,
kern.hostid could be used instead?  That has much better randomness than
'ticks'.

-- 
	Dan Nelson
	dnelson at allantgroup.com