Subject: Re: IEEE802.3 support ??
To: None <firstname.lastname@example.org>
From: None <email@example.com>
Date: 02/19/1999 09:46:31
> I believe that 802.2 addressing is in fact what is used for 802.3,
> so it is "the same" for all IEEE media layers (for some definition of
> the term). Is there something specific that is lacking in this
> Ethernet V2 and 802.2 do indeed coexist on the same wire. The two
> bytes following the source and destination are treated as a packet
> length field for 802.2, if smaller than the Ethernet MTU (1514), and
> as a protocol id for Ethernet V2 if larger than the MTU.
As of today, the Ethernet V2 frame format *is* officially part of the
IEEE 802.x standards. Read recent postings in comp.dcom.lans.ethernet
from Rich Seifert about this.
> Probably, today, it's anyone's guess. IP is almost exclusively V2
> on ethernet (except for some legacy gear from HP and compatible
> implementations). AppleTalk uses 802.2 exclusively. Then there's
> IPX, which, as I understand it, can use any of a handful of
> mechanisms from V2, 802.2 (with and without SNAP headers, ...). I'd
> expect that IP is generally the lion's share, but it really depends
> on the installation.
I made some measurements a few years ago in a reasonably large university
environment. At the time, we routed IP, IPX, Appletalk and DECnet. On the
university backbone, something like 95% of the packets had the Ethernet
type field, while less than 5% had a length field. (Doesn't mean that the
backbone was 95% IP, there was also a good bit IPX with 0x8137 type field.)
Of the total IP traffic, less than 0.1% used a length field.
Steinar Haug, Nethelp consulting, firstname.lastname@example.org