IEEE 802.2, 802.3 & Ethernet questions


Richard Stevens (hsi!stevens@uunet.uu.net)
10 Aug 88 20:30:18 GMT


I have a few questions regarding the use of TCP/IP on an Ethernet.
>From reading RFC 1042, I'm led to believe that "all communication
is performed using 802.2 type 1 communication." That would seem to
imply that the 8-byte LLC header and SNAP header is being used,
but going through our 4.3 BSD sources, I can't find any refernces
to these headers. Later in the RFC, they talk about "Interoperation
with Ethernet", which makes me think that what we're using is the
"Ethernet" instead of the 802.3 link level control.
I can't find many references that describe 802.2 at all - I don't
want to read the IEEE standard (if possible) and Stallings Volume 2
(which the local bookstore doesn't have) appears to be the only
reference I've seen.

(1) What are the differences between Ethernet V1.0 and V2.0 and 802.3 ?
        From seeing how our hardware is set up, it appears that all our
        interface cards are set for 802.3.

(2) Do any TCP/IP implementations on an "ethernet" use the 802.2 LLC ?
        Looking at the RT PC AIX V2.1 manual (pp. 1-17 to 1-19) leads
        me to belive that this implementation does use the 802.2 LLC.

(3) Why do some documents refer to the 2-byte field in the Ethernet
        MAC (immediately following the destination address and source
        address) as "length" (RFC 1042, for example) while others call
        it "packet type" (Comer's new book, for example) ?

(4) Are there any implementations of TCP/IP on a Token-Ring (802.5)
        other than the RT PC ?

Thanks for any light anyone can shed on this.

        Richard Stevens
        Health Systems International, New Haven, CT
           { uunet | yale } ! hsi ! stevens



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