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From: morgan@jessica.stanford.edu (RL "Bob" Morgan)
Newsgroups: comp.dcom.lans,comp.protocols.tcp-ip
Subject: Zero manufacturer code in SNAP?
Message-ID: <1990Jul17.010234.12077@portia.Stanford.EDU>
Date: 17 Jul 90 01:02:34 GMT
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Here's a question about SNAP that might be answered if I could ever
actually see the spec for it.  Then again, maybe not.

The 40-bit SNAP extension to IEEE 802.2 specifies a 24-bit
"organizationally unique identifier" that is apparently supposed to be
the same 24 bits that a manufacturer uses to form the upper part of a
48-bit unique IEEE 802 MAC address.  The other 16 bits are assigned by
the organization in any way it sees fit.

Now, IP on 802.2, as specified in RFC 1042, uses 24 bits of zeros to
fill this field.  The remaining 16 bits are filled with the same 16
bits used for the Ethernet type field (for IP and ARP frames).

The question is, has the all-zeros SNAP id been assigned by IEEE to
DoD, or the IAB, or some IP authority, to be administered by that
authority?  Or is the all-zeros id just a general purpose format for
translating Ethernet frames to 802.2/SNAP, to be used by anyone?
Those of you familiar with AppleTalk Phase II may get a glimmer of why
I'm asking.

Thanks,

 - RL "Bob" Morgan
   Networking Systems
   Stanford