Where is generated the preamble?

The preamble is defined as part of the MAC frame, i.e., it is generated (architecturally) by the MAC.

However, since hardware implementations are not partitioned by abstract architectural considerations, the specific layer/sublayer is irrelevant. The preamble is generated by the Ethernet chip or core.

-- Rich Seifert Networks and Communications Consulting 21885 Bear Creek Way (408) 395-5700 Los Gatos, CA 95033 (408) 228-0803 FAX

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Hi Rich,

Many thanks for your interresting reply.

Thanks for this statement, written like this. I have to note that for my students.

There is a slightly difference between 802.3-2005 (or before) and

In 802.3-2005, figure 3-1, we see that the MAC frame format include the preamble and SFD.

In 802.3-2008, it is mentionned:

Section 1.4.212: "MAC frame: Consists of the Destination Address, Source Address, Length/Type field, MAC Client Data, Pad (if required), and Frame Check Sequence".

Section 1.4.259: "packet: Consists of a MAC frame as defined previously, preceded by the Preamble and the Start Frame Delimiter, encoded, as appropriate, for the Physical Layer (PHY) type".

Thanks for this confirmation.

Thanks for your remarks, best regards, Michelot