RE: [ethmac]

["Kevin Kay" <Kevin.Kay@espipd.com>]

I assume that you are doing a copper interface, so your MAC would have a
GMII interface (8-bits wide) to the PHY rather than a SERDES (10-bits
wide, 8b/10b coded) interface (fiber).  While the gig-E mac is similar
in principle, I think it is slightly different in implementation due to
real-world timing constraints (8-bits wide MII, collision timing
different, etc).

I'm not a gig-E expert, but I seem to remember some minimum packet
length requirements in half duplex mode in order to reliably detect a
collision in the high data-rate environment of gig-E.  If the packet to
be transmitted was not large enough, it had to be padded.  The gigE
requirement was larger than the 64 bytes for 100MBit stuff.  This larger
min packet requirement did not apply in full duplex (since there would
never be a collision).

I'm sure there are many more differences than the 8-bit wide interface
and the half-duplex packet size.

I'm not an author of the opencores code, but I have studied it a great
deal, and I think much of the MAC code would apply if you are doing a
10/100/1000 MAC (you would be using the 10/100 code and adding 1000
support).

In a nutshell, my opinion is that the opencores code would be a great
place to start (especially if doing 10/100/1000), but it will take more
than a few hours to modifiy for 1000 support (no free lunch).

Regards,
Kevin

-----Original Message-----
From: Colin [mailto:colin.renfrew@sli-institute.ac.uk]
Sent: Monday, July 29, 2002 12:43 PM
To: ethmac@opencores.org
Subject: [ethmac]



Hi,
  I'm completely new to this forum. I'm currently working on a project, 
the focus of which is to design the MAC Rx for Gigabit Ethernet, in 
Verilog. At the moment, I have still to begin actual implementation and 
coding.

I stumbled across this mailing list and some of the information I've 
picked out so far looks invaluable to my project. I was wondering if 
anyone has general advice/can help me out with this. The main question 
I have on first glance at this mailing list is: Can all of this be
applied to 
Gigabit Ethernet? If so, what are the main differences?

Ok, any feedback would be greatly appreciated,
Cheers,
Colin
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