Xref: utzoo comp.dcom.lans:4326 comp.protocols.tcp-ip:10232
Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!cs.utexas.edu!swrinde!zaphod.mps.ohio-state.edu!brutus.cs.uiuc.edu!apple!amdahl!twg.com!lefty
From: lefty@twg.com (David N. Schlesinger)
Newsgroups: comp.dcom.lans,comp.protocols.tcp-ip
Subject: Re: Ethernet type 80F3 ?
Message-ID: <151@gollum.twg.com>
Date: 12 Feb 90 18:02:50 GMT
References: <4981@emory.mathcs.emory.edu>
Sender: news@twg.com
Organization: The Wollongong Group
Lines: 30

In article <4981@emory.mathcs.emory.edu> km@mathcs.emory.edu (Ken 
Mandelberg) writes:
> Does anyone recognize ethernet type "80F3"? I don't see it in RFC1010, 
> but I am seeing it on our net.

Ethernet type 0x80F3 is used by AppleTalk for address resolution.  You 
must have Macs on your network which are directly connected to Ethernet.  
These packets are used by the Mac (generally at startup) to determine a valid AppleTalk node number.

There are basically three flavors of AARP (AppleTalk Address Resolution 
Protocol) packets: request, response and probe.  These can be distinguished by the value in the word at offset 20 in the packet: a value of 1 is a Request, 2 is a Response and 3 is a Probe.

Starting at offset 22, these packets will contain the following: a source 
Ethernet address (6 bytes), a source AppleTalk address (4 bytes),  a 
destination Ethernet address (in the case of a Response; 0 otherwise) (6 
bytes), and an AppleTalk address (4 bytes).  Details of what's actually going 
on with these can be found in "Inside AppleTalk", published by 
Addison-Wesley.  See chapters 2 and 3 on "AppleTalk Address Resolution 
Protocol" and "Ethernet Link Access Protocol" respectively.

Hope this helps.

Lefty

===========================================================================
          David N. Schlesinger   || "There's a word for it: words don't
          The Wollongong Group   ||  mean a thing.  There's a name for it;
Internet: Lefty@twg.com          ||  names make all the difference in the
POTS:     415/962-7219           ||  world..." -- David Byrne
===========================================================================