Path: utzoo!attcan!uunet!husc6!bloom-beacon!bu-cs!purdue!decwrl!ucbvax!atom.hpl.hp.COM!norm From: norm@atom.hpl.hp.COM (Norman Kincl) Newsgroups: comp.protocols.tcp-ip Subject: Re: 802 (.2).3 TCP/IP Message-ID: <509.580153365@atom> Date: 20 May 88 17:42:45 GMT References: Sender: daemon@ucbvax.BERKELEY.EDU Organization: The Internet Lines: 27 > I certainly agree that 802.3 is useless, and we should have stuck with > DEC-Intel-Xerox Ethernet. However what seems to be happening in > practice is that older protocols are ignoring 802.3, and newer ones > are using it. Thus no incompatibility actually happens. That is, > TCP/IP, PUP, and DECnet phase IV are using the Ethernet standards, > while ISO and DECnet phase V will presumably use 802.3. For token > rings, etc., that have no existing base of TCP/IP implementations, it > appears that only an 802.3 encapsulation will be used. So we should > not have compatibility problems in practice. That assumes no vendors > get overly eager in their standard-following and try to do an 802.3 > encapsulation for Ethernet. HP did that, and lost obviously enough > that I think other vendors will be discouraged from following suit. Are you not confusing 802.3 with 802.2? 802.3 (physical layer) is essentially identical to Ethernet physical layer (the grounding pin is different and there is one other difference in there somewhere). It is not hard to make a card that can be fully compatible with both. Most cards these days don't really care if they are connected via an transceiver cable to a transceiver (Ethernet) or via an AUI cable to a MAU (802.3). 802.2 (data link layer) is where the problem comes in. Though you can have a system that speaks both quite fluently (eg. HP9000 or cisco box), most systems do not do that and provide only one of those data link layers (usually Ethernet). (There is no such thing as 802.3 token ring---that comes under 802.5)