Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP Posting-Version: version B 2.10.2 9/18/84 SMI; site sun.uucp Path: utzoo!linus!decvax!decwrl!sunny From: sunny@sun.uucp (Sunny Kirsten) Newsgroups: net.lan Subject: Re: Ethernet 1 vs. Ethernet 2 vs. 802.3 Specifications Message-ID: <1786@sun.uucp> Date: Sat, 10-Nov-84 16:45:51 EST Article-I.D.: sun.1786 Posted: Sat Nov 10 16:45:51 1984 Date-Received: Mon, 12-Nov-84 07:20:28 EST References: <4178@decwrl.UUCP> Organization: Sun Microsystems, Inc. Lines: 33 > The changes between Ethernet 1 and 2 (most of which were adopted by the > 802.3 committee) were instituted to correct problems with Ethernet 1 and > to improve the system reliability and maintainability... > > 802.3 and Ethernet 2 are quite similar... The most significant differerence > is in the frame format, a software (driver) issue in most implementations. > > As a member of the 802.3 committee when it was adopting the standard I can > assure you that compatibility with existing equipment was a key concern. Ok, so how do I add new Ethernet 2 spec systems to an existing Ethernet 1 network in a compatible fashion? How does my (new) driver know when it receives a packet off the net, whether it's an Ethernet 1 or 2 packet? How do I interpret the packet type field, which changes from 2 bytes to 6, if I remember correctly? Has the definition of the 6-byte packet type field been constrained to upward compatibility with the older Ethernet 1 2-byte type field? Or do I have to convert my entire network from Ethernet1 to Ethernet2... i.e., can they coexist on the same cable? If not, why not? What does an Ethernet2 compatible driver do to recognize an old 2-byte packet type field followed by 4 bytes of packet data, from a new Ethernet2 6-byte type field? I wasn't on the comittee, but know someone who was, who was the source of the idea that there were purposeful incompatibilites foisted by other reps. I do not judge that data, just forward it. It could be all wrong. It's nice to hear the opposing point of view...which is more encouraging for the future of the Ethernet standard(s). It's nice to have two datapoints versus one. Has anyone got an Ethernet running which supports both standards simultaneously? Or are they truly mutually incompatible? -- mail ucbvax\!sun\!sunny decvax\!sun\!sunny ihnp4\!sun\!sunny<