🚀 go-pugleaf

Jim Dawson wrote:
> 
> bainster@interramp.com wrote:
> 
> >Phil Randal <philr@hwcces.demon.co.uk> wrote:
> >
> >>In article <4uasq3$s0m@caladan.restena.lu>
> >>   marcel.cox@cie.etat.lu (Marcel Cox) writes:
> >>>First 2 things to clear up:
> >>>
> >>>- Packet burst works with any frame type
> >>>
> >>>- The only thing that does not work with all frame types is IPX
> >>>checksums( this is not packet signature). This does not work with
> >>>Ethernet_802.3.
> >>>
> >>>As for what frame type is best, I think everyone has its own favorite.
> >>>I think Ethernet_SNAP is the only frame type that nobody recommends
> >>>using.
> >>>Personally I prefer using Ethernet_802.2 as it is the default frame
> >>>type for Netware 3.12 and 4.x and it minimizes the risk of selecting
> >>>the wrong frame type.
> >
> >>If you're _ever_ going to run TCP/IP on your network, go for Ethernet_II
> >>frame type.  Shucks, go for it anyway:-)
> >
> >Either that or Ethernet_SNAP.  No other choice ..
> 
> Could someone post a list of pros and cons of using each of the four
> frame types supported by NetWare? (802.3, 802.2, Ethernet II, Ethernet
> SNAP)
> 
> Also, I was told that NetWare 4.x does not work properly with 802.3. Is
> there any truth to this?
> ---
> +----------------------------------------------------------------------+
> | <*>                Jim Dawson - jdawson@inlink.com               <*> |
> +----------------------------------------------------------------------+



Let's see. In the beginning there was the Digital-Intel-Xerox (DIX)
standard,called 'Ethernet', then there came version two of the same
(which I believe only differed in the physical spec's). The DIX Ethernet
frame-type contained a TYPE field which contained a number that
described the what kind of OSI3-data it was carrying (i.e. XNS, IP,
..)..

Then came IEEE which combined elements of LAPB (Data-link connections,
and other stuff) with Ethernet and ripped out the TYPE field and made it
a LENGTH field instead. A new part of the fram called LLC (Logical Link
Control) now had TYPing capability (for both sending and receiving
protocols, which truly IS wierd.. I mean when, if ever, do you want to
send from IP to IPX???). This standard was christened 802.3.

For reasons that are rather unclear to me, Novell made a proprietary
version of "802.3" that they also named "802.3", but which was missing
the LLC-field, so that it was unable to tell what kind of data it
carried. Of course, if the only type of data you'll carry is IPX, then
that's OK, I guess. The whys and wherefores of this as acording to
rumors that Novell made their version before IEEE was ready with theird.
I dunno.

Anyway the (IEEE) 802.3 was a standard - presto - but programmers still
wanted to be able to use the same type values as in the DIX Ehternet
standard (or so I have been told ... OK, I have read it somwhere.
Whatnot..  :-) So the Ethernet_SNAP unstandard ethernet-frame was
created. It's actually a version of (IEEE) 802.3, but with a
"SNAP"-field after the LLC. What does the SNAP-filed do?  It types the
data. But didn't LLC do that??? Yes! But with different kind of numbers
than the DIX standard.

So SNAP wastes (i believe) 4 bytes on saying "SNAP coming up" in the LLC
field, and then the SNAP field comes along with types the data after the
same fasion tha the DIX ethernet frame's type field did. URG.

So what we have here is the following; Ethernet, which Novell calls
Ethernet_ii,
802.3, which Novell calls Etehrnet_802.2 (because the LLC field is also
named 802.2 (1980 february, subgroup 2 - think)), and we have the very
very nonstandard inflexible tpe of ethernet which sometimes is referred
to as "802.3 (RAW)", but which Novell merrily calls Ethernet_802.3, even
though it absolutely isn't and lacks a vital component which the
standard going by the same name has, and we have the Ethernet SNAP
nonstandard, which Novell calls Ethernet_SNAP.

You didn't really want to know thi, though, did you??

Peter Svensson
MCNE, CNI, Programmer, and so on..
Data Construction Education AB
Sweden
psvensso@eiknes.se