Reserved MAC-addresses (some are assigned anyway?)
Was looking into this myself.. I know it's been a while since the post was active.. but I found these to be ok to use locally:
- x2-xx-xx-xx-xx-xx
- x6-xx-xx-xx-xx-xx
- xA-xx-xx-xx-xx-xx
- xE-xx-xx-xx-xx-xx
Source: https://honeywellaidc.force.com/supportppr/s/article/Locally-Administered-MAC-addresses
The following OUI are reserved as per RFC 5342:
OUI 01:00:5E:(00:00:00-7f:ff:ff) - Used for IPV4 Multicast and MLPS Multicast.
OUI 00:00:5E:(00:01:00 – 00:01:FF) - Used for Virtual Router Redundancy Protocol (VRRP) IPV4
OUI 00:00:5E:(00:02:00 – 00:02:FF) - Used for Virtual Router Redundancy Protocol (VRRP) IPV6
OUI 33:33:00 – 33:33:FF - Reserved for IPV6 Multicast
OUI CF:00:00 – CF:FF:FF - Reserved by IANA for PPP(Point to Point Protocol)
OUI 00:00:5E (00:00:00 - 00:00:FF) - Requires IESG Ratification for allocation.
I was just looking into this myself recently. I believe that the IANA (which you refer to in one of your links) will give the most authoritative answer: IANA Ethernet Number Assignments
I don't think that this means that these addresses can never be used though. According to RFC5342, Section 2.1
"The 2**8 unicast identifiers from 00-00-5E-00-00-00 through 00-00-5E-00-00-FF are reserved and require IESG Ratification for allocation (see Section 5.1)."
So basically, it appears you need special permission from IESG (Internet Engineering Steering Group) to get an address in that range, which I suppose the ISI has obtained somehow.
Section 2.1 of RFC5342 deals with 48-Bit MAC Identifiers and OUIs, and it doesn't make any mention of any address ranges that are strictly forbidden or permanently reserved from what I've understood.