Thread Links Date Links
Thread Prev Thread Next Thread Index Date Prev Date Next Date Index

Re: [STDS-802-Privacy] Locally-administered bit and OUI registration

Any local administrator can use locally administered addresses however they want. There are very few rules beyond that the local bit has to be one and the individual/group bit having its usual meaning. 

If a product always uses it's OUI to form local addresses, that might conflict with addresses assigned by a local administrator. If it's an option that a local administrator can turn off or on depending on the way the administrator wants to use the address space, that isn't an issue.

There are some special cases where conflict with other locally administered addresses is less of a concern: e.g. when the address is used only during establishment of a connection to an access point or addresses used vehicle to vehicle (because there isn't any administrator, there is negligible time to go through an address assignment protocol, and the pool for conflict is a small number of devices.)

We have a project underway to describe an optional space plan for the local address space where CIDs are used to form local addresses. That would be another option.

On Wed, Sep 21, 2016 at 6:29 AM, Matte Célestin <celestin.matte@xxxxxxxxxxxx> wrote:

Thanks for the answers.

I found answers to my questions in this document:
"all OUI assignments made by the IEEE RA have M and X bits equal to
zero." →  otherwise, they're CID, and
"Use of a CID is appropriate when MAC addresses are not needed"
The document also discusses how CID can be used to generate
locally-administered, not globally unique MAC addresses.
The point is that IEEE does not indeed assign OUI with LA bit set to 1
(otherwise they're called CID and can't be used for MAC addresses).

Furthermore, this note responds to my comment about invalid OUI in the
oui.txt file:
"NOTE – A very small number of assignments made prior to adoption of
IEEE 802 standards have the X bit equal to one (BlockID assignments)."

Célestin Matte