installing new ethernet address equipment with VMS 6.1

Gil> There is another concept called Locally Administered Gil> Addresses. ... Gil> So, instead of using the burned in MAC address you would use a Gil> Locally Administered address. The LAA bit is the second bit on Gil> the wire. Ethernet puts the LSb of each byte on the wire first, Gil> so a LAA Ethernet address would be one with the 2 bit on. Token Gil> Ring put the MSb on the wire first, so an LAA address typically Gil> started with 0x40. Gil> DEC might not have supported LAAs in any given environment, of Gil> course. But I doubt if the 802.3 spec specifically exempts a Gil> VMSCluster. ;) Of course it doesn't. DEC used locally administered addresses all the time -- the DECnet style MAC address is aa-00-04-00-xx-yy so it's locally administered, as indeed it should be given the definition. Gil> DEC was an early player in this area. After all, DIX Ethernet Gil> format refers to DEC, Intel & Xerox. They did all manner of Gil> strange things. For example, the first three bytes of a MAC Gil> address are the vendor code. DEC used 4, and on a given adapter Gil> they might use any of the 4 possible variants of the MAC address Gil> using the same low order 3 bytes but varying the high order 3 Gil> bytes to any of their 4 vendor codes. This is one reason why Gil> Ethernet switches can usually learn at least 4 MAC addresses per Gil> port. That doesn't match any DEC practice I know of, and I was the DEC address administrator at one time so I should know... You may be confused with the DECnet address. DECnet phase IV uses MAC addresses formed from the DECnet node address: aa-00-04-00-xx-yy where xx is the low order and yy the high order of the 16 bit node address. Some NICs were capable of keeping their "real" MAC address alive at the same time, which was good for LAT; others would use this LAA for all traffic, which meant you had to be sure to turn DECnet on before LAT. Before IEEE got into networking, DEC was assigned company codes (later named "OUI) aa-00-01 through aa-00-04. And indeed some early NICs, like the DEUNA, were shipped with MAC addresses like that. In addition, some multicast addresses for DEC protocols are derived from these (they start with AB-00-...). After IEEE started changing Ethernet around, defining the notion of locally administered addresses in the process, DEC obtained OUI 08-00-2B which was then used across the board. I think the earlier assignments were officially grandfathered but even so we stopped using them for new hardware to avoid confusion. DEC also owned OUI 00-00-F8 but I don't know if that was ever used for MAC addresses; it did get used for 802.2 SNAP protocol identifiers for bridging from FDDI to Ethernet, in a very confusing and strange story... paul