Re: Software to test MAC address privacy

On 08/03/2014 04:58 AM, Glen Turner wrote:
On 19/07/2014 Robert Moskowitz wrote:
Actually the standard uses the first 2 bits for this. It is called local scope MAC addresses. This leaves 46 
bits for the random content. Thus if you have a network of 10000 devices the probablity of a collision is 
Hello Robert,

Not all locally-assigned addresses are available for use as random MAC addresses. Last I looked that are 
historical uses of LAS for DECnet and other protocols from 00:… through to 05:…. It would be useful if the 
IEEE recommended a range of LAS for host use (ie, virtual machine MAC addresses) and specified a range for 
your random MAC address proposal. Such a range should leave sufficient LAS for other potential future 

This is actually in progress. We are forming a study group in IEEE 802 (first session will be at the November San Antonio meeting) to fully document this and come out with a recommended practice. One of the other drivers is the cloud computing world. There is talk about partitioning the use of the LAS. I am against that as it increases the collision probablity. Perhaps by usage domain.

In any case we will have to work out probe/discovery methods to discover collisions for readdressing.

thanks for your input.  I will see it gets included in the discussion.

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