Hi Jon, There could be a little overlap, true.
But in practice it's not a problem as IPv6 addresses generated from Ethernet MAC addresses will have the Universal/Local (U/L) bit of the IPv6 address set to indicate it is a globally unique address. Whereas the IPv6 address generated from an 802.15.4 short address will have this but clear, since it's not globally unique. Hence the IPv6 address from your Xerox MAC will in fact become fe80::200:0ff:fe00:1. Regards, -Colin -----Original Message----- From: [email protected] [mailto:[email protected]] On Behalf Of Jon Smirl Sent: August 22, 2010 1:27 PM To: [email protected] Subject: [6lowpan] Generated IID from short addresses. A short IEEE 802.15.4 address is 16 bits in length. Short addresses are mapped into the restricted space of IEEE EUI-64 addresses by setting the middle 16 bits to 0xfffe, the bottom 16 bits to the short address, and all other bits to zero. As a result, an IID generated from a short address has the form: 0000:00ff:fe00:XXXX Doesn't this section cause problems with the Xerox OUI? If I have a Xerox Ethernet card with a 48b MAC address of 0x1 it will generate a link local address of fe80::ff:fe00:0001 when the 48b address is expanded to 64b. An 802.15.4 short address will generate the same link local address. Now I doubt that any of the first 64K Ethernet addresses are still in use, but to keep everything truly unique shouldn't there be an IEEE assigned OUI for 802.15.4 short addresses? http://standards.ieee.org/regauth/oui/index.shtml With a 24b OUI assigned the whole 64b address space become usable. For example aaaa:aa00:panid:short where aaaaaa is the OUI. The OUI of 80:21:54 hasn't been assigned, it would be a good choice. -- Jon Smirl [email protected] _______________________________________________ 6lowpan mailing list [email protected] https://www.ietf.org/mailman/listinfo/6lowpan _______________________________________________ 6lowpan mailing list [email protected] https://www.ietf.org/mailman/listinfo/6lowpan
