From mboxrd@z Thu Jan  1 00:00:00 1970
From: Stephen Hemminger <shemminger@vyatta.com>
Subject: Re: [net-next PATCH] igb: Use Intel OUI for VF MAC addresses
Date: Thu, 10 Sep 2009 19:07:03 -0700
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Cc: davem@davemloft.net, netdev@vger.kernel.org, gospo@redhat.com,
	Greg Rose <gregory.v.rose@intel.com>,
	Jeff Kirsher <jeffrey.t.kirsher@intel.com>,
	Don Skidmore <donald.c.skidmore@intel.com>
To: Jeff Kirsher <jeffrey.t.kirsher@intel.com>
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On Thu, 10 Sep 2009 18:48:27 -0700
Jeff Kirsher <jeffrey.t.kirsher@intel.com> wrote:

> From: Gregory Rose <gregory.v.rose@intel.com>
> 
> This patch changes the default VF MAC address generation to use an Intel
> Organizational Unit Identifier (OUI), instead of a fully randomized
> Ethernet address.  This is to help prevent accidental MAC address
> collisions.

How can probability of collision be lower when the address space
is smaller? If you are going to use Intel OUI, then you should constrain
the selection to a portion of that space that is not being used
by other hardware. I.e if you know Intel assigns addresses to their
devices in ranges, choose a range that is not in use.