"Billy Monroe" <[EMAIL PROTECTED]> wrote,
>I see a description of the differences between them but I can't really
>understand that in practical terms.
Depends what you mean by "practical." Ethernet II is an older standard.
>Is the IEEE 802.3 the CSMA/CD ?
No. Both use CSMA/CD (ignoring special cases of Fast and Gigabit speeds)
>
The February CCIE paper at http://www.certificationzone.com, CCIE
Switching Part 1 by Dan Farkas, goes into this in more detail.
Briefly, both the original Ethernet and 802.3 cover more than one OSI
layer, although 802.3 assumes 802.2 will run on top to complete the
data link layer.
Layer 1 differences: minor. Ethernet has an interface signal
variously called SQE or heartbeat, which 802.3 does not.
Layer 2 differences: after the preamble, both Ethernet and 802.3
have a destination MAC address, a source MAC address, followed by a
two-byte field. The usage of this two-byte field is different in the
two protocols.
In Ethernet, it carries an Ethertype code that identifies the
protocol of the payload in the user data field.
In 802.3, it carries the frame length. Protocol identification is
the job of the 802.2 header, which occupies the first few bytes of
the user data field. Note: there is one Novell variant in which
there is no 802.2.
802.1Q VLANs and other 802 standards can complicate things, but are
beyond the scope of this answer.
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