Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP Posting-Version: version B 2.10.1 6/24/83; site fortune.UUCP Path: utzoo!watmath!clyde!burl!ulysses!harpo!ihnp4!fortune!rpw3 From: rpw3@fortune.UUCP Newsgroups: net.lan Subject: Re: Ethernet addressing - (nf) Message-ID: <3316@fortune.UUCP> Date: Tue, 15-May-84 19:05:52 EDT Article-I.D.: fortune.3316 Posted: Tue May 15 19:05:52 1984 Date-Received: Wed, 16-May-84 04:42:33 EDT Sender: notes@fortune.UUCP Organization: Fortune Systems, Redwood City, CA Lines: 54 #R:hao:-96700:fortune:5900021:000:2232 fortune!rpw3 May 15 15:10:00 1984 +-------------------- | Is it true that all Ethernet devices have a unique address,... +-------------------- They'd damned well better! That's why they are 48 bits. (Although somebody somewhere will, from time to time, screw up in their manufacturing and Q/A and have to come around and fix it. ;-} ) +-------------------- | ...or must one make a special effort to obtain one from some organization? | If so, what is the organization, and what are the advantages/disadvantages? +-------------------- If you are just buying controllers from some vendor such as 3Com or Interlan, not to worry. The controller comes with a default address which is (supposed to be) unique, set by the vendor. Note: If you are going to be a gateway host between two Ethernets, make sure your controllers can have the address overridden by host software, since it is very important that the same absolute physical address appear on both nets. (Usually, you go read the default addresses from all the controllers, pick one [the smallest? the "first"?], and write that to all of them.) If you are manufacturing controllers, you will need a license from Xerox to use the Ethernet patent ($1000, one-time). With that license, you get a (LARGE!) block of numbers to use to give unique numbers to your controllers. It you just want a block of globally-unique numbers, I think Xerox will also sell you a block of Ethernet addresses (with NO patent license) for $500. There is no real advantage in getting your own addresses, as opposed to using the ones that come with your controllers. (In fact, should you write any software that depends of the manufacturer-specific 24 bits of the address, you would deserve to get your hands slapped!) In any event, for more details go to the source (Appendix "B" of the spec): Xerox Corporation Ethernet Address Administration Office 3333 Coyote Hill Road Palo Alto, CA 94304 Packet types and network numbers are also registered through the same office. (Note: ALL of IP/TCP uses merely one packet type. Ditto all of XNS/ITP.) Rob Warnock UUCP: {ihnp4,ucbvax!amd70,hpda,harpo,sri-unix,allegra}!fortune!rpw3 DDD: (415)595-8444 USPS: Fortune Systems Corp, 101 Twin Dolphin Drive, Redwood City, CA 94065