Path: utzoo!utgpu!news-server.csri.toronto.edu!clyde.concordia.ca!uunet!samsung!usc!ucsd!ucbvax!VENERA.ISI.EDU!braden
From: braden@VENERA.ISI.EDU
Newsgroups: comp.protocols.tcp-ip
Subject: Re: Zero manufacturer code in SNAP?
Message-ID: <9008062209.AA01185@braden.isi.edu>
Date: 6 Aug 90 22:09:24 GMT
Sender: daemon@ucbvax.BERKELEY.EDU
Organization: The Internet
Lines: 48


	From tcp-ip-RELAY@NIC.DDN.MIL Sun Jul 22 05:40:28 1990
	Date: 20 Jul 90 18:31:49 GMT
	From: agate!shelby!portia.stanford.edu!jessica.stanford.edu!morgan@ucbvax.Berkeley.EDU  (RL "Bob" Morgan)
	Organization: Academic Information Resources
	Subject: Re: Zero manufacturer code in SNAP?
	References: <1990Jul17.010234.12077@portia.Stanford.EDU>, <9272@goofy.Apple.COM>
	Sender: tcp-ip-relay@nic.ddn.mil
	To: tcp-ip@nic.ddn.mil

...

	Now, as Vernon points out:

	> It should be noted in passing that following is in the Host Requirements
	> standard, RFC-1122:
	> 
	> ]      2.3.3  Ethernet and IEEE 802 Encapsulation
	> ]      ...
	> ]         Every Internet host connected to a 10Mbps Ethernet cable:
	> ]
	> ]         o    MUST be able to send and receive packets using RFC-894
	> ]              encapsulation;
	> ]
	> ]         o    SHOULD be able to receive RFC-1042 packets, intermixed
	> ]              with RFC-894 packets; and
	> ]
	> ]         o    MAY be able to send packets using RFC-1042 encapsulation.

	This ensures that IP stations, even if they prefer RFC-1042 (SNAP with
	zero OUI) format, will properly receive Ethernet format.  Of course,
	as Vernon notes, it effectively prevents RFC-1042 from ever being the
	preferred format.

I want to comment on this.  The decision of the Host Requirements Working
Group on this matter was not prompted by a desire to impede the adoption
of 802.3 as an Ethernet replacement, but rather by the desire to make 
things interoperate as well as possible, recognizing that existing
usage is predominantly Ethernet.  Indeed, we rather assumed that over
the long term 802.3 will gradually replace Ethernet, and that some
future Host Requirements revision might interchange the Ethernet 
and 802.3 requirements (i.e., MUST 802.3, MAY Ethernet).  I believe
that the perceived advantage of using an international standard over
a vendor standard will be the force driving this change -- the same
forces driving OSI to replace TCP/IP (he said with a straight face).

Bob Braden