Ethereal-users: Re: [Ethereal-users] IPX Frame Type

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From: Guy Harris <gharris@xxxxxxxxx>
Date: Tue, 14 Dec 2004 23:50:15 -0800
Claudio Antonioli wrote:
All my scans show a frame type of 802.3, although the PCs in the office, as well as the servers, run frame type 802.2.

Ethereal doesn't display the "frame type" in the Netware sense. 802.2 and 802.3, in Ethereal, refer to the IEEE standards in question; 802.3 refers to packets that follow that standard and that have a length field rather than a type field ("Ethernet II" refers to the packets with the a type field), and 802.2 refers to the headers for *that* standard, which are used not only with 802.3-with-length-field Ethernet packets but also with Token Ring, FDDI, 802.11, etc. packets.

According to Don Provan's document:

	http://www.ee.siue.edu/~bnoble/comp/networks/frametypes.html

there are four frame types for Netware:

802.2 - this is 802.3-with-a-length-field on Ethernet, and just the standard link-layer type for Token Ring, etc., plus an 802.2 header with a DSAP that specifies Netware;

	802.3 - this is 802.3-with-a-length-field and *NO* 802.2 header;
	
Ethernet II - this is 802.3-with-a-type-field (a/k/a "DIX (DEC-Intel-Xerox) Ethernet" or "Ethernet II" (as in "successor to the original experimental 3Mb Ethernet), with an Ethernet type value that specifies Netware;

Ethernet SNAP - this is 802.3-with-a-length-field, and just the standard link-layer type for Token Ring, etc., plus an 802.2 header with 0xAA as the DSAP and SSAP, followed by a SNAP header with an OUI of 000000 meaning "Encapsulated Ethernet" and a PID (which, with an OUI of 000000, is an Ethernet type) that specifies Netware.

So "Frame type 802.2" is probably 802.3 and 802.2, so Ethereal will show both 802.3 and 802.2, which is what it should display.