Ethernet 2.0 vs. IEEE 802.3 vs. DEUNA/DELUA

[Steven Bellovin]

We're planning on ordering some DEC DELUAs for some new machines, to save
slots, power, etc., over the older DEUNA.  The good folks at the DEC Technical
Hotline assure me that the two are program-compatible, etc.  However...

The DEC catalogs I have say that the DELUA is compatible with both Ethernet 2.0
and IEEE 802.3, whereas I had thought that the difference was just in the
packet format (i.e., the type field vs. the length).  Furthermore, they say
that the DEUNA is not compatible with IEEE 802.3.  And they have a different
transceiver cable for 802.3 use than for Ethernet use.  Can anyone explain
what's really going on?

(While you're at it, we're also ordering DEC H4005-A transceivers; these -- the
replacements for the H4000s -- are also claimed to be 802.3 and Ethernet
compatible, whereas the H4000s are alleged to be Ethernet-only.  If we have
a DELUA and a H4005-A, to talk to an existing Ethernet, which transceiver cable
do we use?)

Please reply by mail; I'll post any answers that seem helpful.

		--Steve Bellovin
		AT&T Bell Laboratories
		{ucbvax,unc,ihnp4,allegra, most of BTL}!ulysses!smb