Em 10/6/2010 12:09, Peter escreveu:
> Isaac Marino Bavaresco <isaacbavaresco <at> yahoo.com.br> writes:
>   
>> Does the switch chip have multiple MAC+PHY, memory buffer, plus one
>> PHY-like interface to communicate with the MCU?
>>     
> Most embedded MCUs with multiple Ethernet connections actually have two, and one
> of them is attached to an embedded hub (not switch). Also many will use just one
> MAC and present it on both interfaces (WAN and internal hub), since those are
> normally disjoint. They also usually offer the 'clone MAC address' option to the
> user so a more reasonable MAC can be presented to the WAN (copied from a LAN
> client), which MAC is also needed for authentication on the WAN in certain cases.
>   

I think we are talking about different "MACs" here. I'm referring to the
"Media Access Controller", and you apparently to the "MAC address"
(Media Access Control Address).

>From Wikipedia:
"The MAC handles the high level portions of the Ethernet protocol
(framing, error detection, when to transmit, etc) and the PHY handles
the low level logic (4B/5B encoding/decoding, SERDES
<http://en.wikipedia.org/wiki/SerDes> (serialization/deserialization),
and NRZI encoding/decoding) and analog portions."

<http://en.wikipedia.org/wiki/Reduced_Media_Independent_Interface>


Isaac

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