http://www.erg.abdn.ac.uk/users/gorry/course/lan-pages/mac-vendor-codes.html

Ethernet MAC
Ethernet hardware addresses are 48 bits, expressed as 12 hexadecimal digits (0-9, plus A-F, capitalized). They might be written unhyphenated (e.g., 123456789ABC), or with one hyphen (e.g., 123456-789ABC), but should be written hyphenated by octets (e.g., 12:34:56:78:9A:BC). This gives a theoretical 281,474,976,710,656 addresses. This is more than 56,000 MAC addresses for each person on the planet! In practice, the address assignment policy (using flad addressing) will inevitably lead to some wastage - but even so, there are likely to be enougth addresses for ever computer, piece of networking equipment and a large numebr of household/office devices (heating systems, ovens, washing machines, fridges, drinks dispensors, security alarms, video recorders, ...) which could in the future be internet enabled!!!

Source Address Assignment
The 12 hex digits of source address consist of the first/left 6 digits (which should match the vendor of the Ethernet network interface) and the last/right 6 digits which specify the interface serial number for that interface controller vendor (this gives 256 cubed addresses - or 16.78 million separate serial numbers).This allows each vendor to assign their own interface serial numbers (this is a flat addressing scheme), but also allows protocol monitors to examine the first 3 bytes of a frame address to determine the manufacturere of the interface card being used.

The addresses associated with interface cards are source addresses, not multicast nor broadcast, so the second hex digit (reading from the left) will be even, not odd. The following list identifies some of the blocks of assigned vendor MAC addresses (i.e. the first 3 bytes of a MAC source address). As an example, the Ethernet address:

08 00 20 00 70 DF

corresponds to an interface manufactured by Sun Microsystems (see below).

A more complete list follows:

00000C Cisco
00000E Fujitsu
00000F NeXT
000010 Sytek
00001D Cabletron
000020 DIAB (Data Intdustrier AB)
000022 Visual Technology
00002A TRW
000032 GPT Limited (reassigned from GEC Computers Ltd)
00005A S & Koch
00005E IANA
000065 Network General
00006B MIPS
000077 MIPS
00007A Ardent
000089 Cayman Systems Gatorbox
000093 Proteon
00009F Ameristar Technology
0000A2 Wellfleet
0000A3 Network Application Technology
0000A6 Network General (internal assignment, not for products)
0000A7 NCD X-terminals
0000A9 Network Systems
0000AA Xerox Xerox machines
0000B3 CIMLinc
0000B7 Dove Fastnet
0000BC Allen-Bradley
0000C0 Western Digital
0000C5 Farallon phone net card
0000C6 HP Intelligent Networks Operation (formerly Eon Systems)
0000C8 Altos
0000C9 Emulex Terminal Servers
0000D7 Dartmouth College (NED Router)
0000D8 3Com? Novell? PS/2
0000DD Gould
0000DE Unigraph
0000E2 Acer Counterpoint
0000EF Alantec
0000FD High Level Hardvare (Orion, UK)
000102 BBN BBN internal usage (not registered)
0020AF 3COM ???
001700 Kabel
008064 Wyse Technology / Link Technologies
00802B IMAC ???
00802D Xylogics, Inc. Annex terminal servers
00808C Frontier Software Development
0080C2 IEEE 802.1 Committee
0080D3 Shiva
00AA00 Intel
00DD00 Ungermann-Bass
00DD01 Ungermann-Bass
020701 Racal InterLan
020406 BBN BBN internal usage (not registered)
026086 Satelcom MegaPac (UK)
02608C 3Com IBM PC; Imagen; Valid; Cisco
02CF1F CMC Masscomp; Silicon Graphics; Prime EXL
080002 3Com (Formerly Bridge)
080003 ACC (Advanced Computer Communications)
080005 Symbolics Symbolics LISP machines
080008 BBN
080009 Hewlett-Packard
08000A Nestar Systems
08000B Unisys
080011 Tektronix, Inc.
080014 Excelan BBN Butterfly, Masscomp, Silicon Graphics
080017 NSC
08001A Data General
08001B Data General
08001E Apollo
080020 Sun Sun machines
080022 NBI
080025 CDC
080026 Norsk Data (Nord)
080027 PCS Computer Systems GmbH
080028 TI Explorer
08002B DEC
08002E Metaphor
08002F Prime Computer Prime 50-Series LHC300
080036 Intergraph CAE stations
080037 Fujitsu-Xerox
080038 Bull
080039 Spider Systems
080041 DCA Digital Comm. Assoc.
080045 ???? (maybe Xylogics, but they claim not to know this number)
080046 Sony
080047 Sequent
080049 Univation
08004C Encore
08004E BICC
080056 Stanford University
080058 ??? DECsystem-20
08005A IBM
080067 Comdesign
080068 Ridge
080069 Silicon Graphics
08006E Concurrent Masscomp
080075 DDE (Danish Data Elektronik A/S)
08007C Vitalink TransLAN III
080080 XIOS
080086 Imagen/QMS
080087 Xyplex terminal servers
080089 Kinetics AppleTalk-Ethernet interface
08008B Pyramid
08008D XyVision XyVision machines
080090 Retix Inc Bridges
484453 HDS ???
800010 AT&T
AA0000 DEC obsolete
AA0001 DEC obsolete
AA0002 DEC obsolete
AA0003 DEC Global physical address for some DEC machines
AA0004 DEC Local logical address for systems running DECNET
Note that the first byte of the source address is always even (since the least significant bit, or first bit on the wire indicates that the address is a group address ).

Destination Address Assignment
The destination address is a valid source address, except for an address which has the lowest bit of the first byte set to '1'. These addresses, including the all 1's broadcast address FF:FF:FF:FF:FF:FF and the set of multicast addresses, are point-to-multipoint addresses and can never appear as the source address in an Ethernet frame. A frame must be sent by a single source. Can you imagine the complications which would arise with learning bridges if this rule was not kept?


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Gorry Fairhurst - email:G.Fairhurst@eng.abdn.ac.uk - Date: 01/01/2001 EG3557