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From: donp@na.excelan.com (don provan)
Newsgroups: comp.dcom.lans
Subject: Re: Ethernet Vs. IEEE 802.3 ??????????
Message-ID: <2508@excelan.COM>
Date: 19 Dec 90 23:03:12 GMT
References: <13213@uudell.dell.com>
Sender: news@excelan.COM
Reply-To: donp@novell.com (don provan)
Organization: Novell, Inc., San Jose, California
Lines: 25

In article <13213@uudell.dell.com> mjhammel@Kepler.dell.com (Michael J. Hammel) writes:
>The type field of ethernet
>is, I've been told, always less than some number and the length field of
>802.3 is always greater than that number.

This is backwards, probably just a typo.  The maximum legal 802.3
length is 1500.  Anything value larger than that is an ethernet type.

>  This *might* be a way to tell
>the two frame types apart, but don't count on it.

On the contrary, you can count on it because it's in the 802.3 spec.
(Well, sort of: the spec has a famous footnote which says that packet
lengths larger than the maximum 802.3 length have some unspecified
local meaning.  I've yet to hear of an 802.3 network where that "local
meaning" was something other than "ethernet type".)

The only "illegal" ethernet types i've ever heard of were a couple of
ancient Xerox PUP values that fell below the 1500 value.  Both of them
were reallocated legal values long ago, so i wouldn't expect to see
any software using the old values.  Actually, i'm not sure i'd expect
to see any software using the new values, either, since i don't
believe PUP is used much any more.
						don provan
						donp@novell.com