RE: [ethmac] Standard info.

[Javier_castillo_villar@yahoo.es]

 Hi:

   I am talking about 100basetx ethernet. In 100basetx you trasmit at 
125 Mbps because you use only one cable and a 4B/5B coding so if you 
want to oversample by four you must have a 500Mhz clock, so i think 
itīs better a external PLL. Itīs in 100baset4 where you use four cables 
and you trasmit at 25Mbps on each so you have 25*4=100Mbps.
  Itīs a goog idea to capture some frames if you do it you will see that 
the preamble are not 64 bits of length it can be 62 or 69 or a number 
near to 64, you find the begin of the frame when you find a 11 at the 
end of the preamble. You must note that the probably the standard you 
have is IEEE 802.3 but the windows lans use dix ethernet 2. The mac in 
opencores is ethernet 2, itīs basically the same but have small 
differences you probably know. 
 The companies donīt use only the standard for work. There is a 
organization which certifies that products are ethernet standard 
compatible. They sell all the information you need to make your 
ethernet full compatible and then they certifies it. There is a lot of 
money behind this and the companies donīt want more competence. 




----- Original Message ----- 
From: "Illan Glasner" <iglasner@z... > 
To: <ethmac@o... > 
Date: Mon, 22 Apr 2002 10:02:52 -0700 
Subject: RE: [ethmac] Standard info. 

> 
> 
> 22-Apr-02 
> 
>    Javier Hi, 
> 
>       Two small point. 
> 
> Why do you think you Must have external PLL for Fast-Eth ? don;t 
> forget it is only 25M and 40n period . 
> 
> The IEEE std does cover all frame I would agree it is not always 
> clear and easy to read but you should be able to find anything in 
> it, just imagine what would happen if it is not explaining all 
> frame and each company try to make her own version ... 
> 
> have a nice day 
> 
>    Illan 
> 
> 
> 
> -----Original Message----- 
> From: Javier_Castillo_Villar@y...  
> 
> [/cgi-bin/post.cgi?cmd=new&to=Javier_Castillo_Villar%20at%
20yahoo%20dot%20es&msg=/ml-archive/ethmac/msg00043.shtml] 
> Sent: Thursday, April 18, 2002 2:10 AM 
> To: ethmac@o...  
> Subject: RE: [ethmac] Standard info. 
> 
> 
>  There is few information about ethernet. The only font of 
> information is 
> the IEEE 802.3 standard but at this moment you must pay for it. 
>  I am for university of cantabria in spain and actually we are 
> working on 
> a phy and mac core for ethernet in VHDL. It is a small core, it 
> donīt 
> have all the standard features, but we hope it works. Itīs only a 
> 10 
> base t core not 100 because we only want a vhdl core that we can 
> program in a spartan 2 fpga. If weīll do a 100 Mbps core we need a 
> PLL 
> outside the fpga so we are not interested in. 
>  We have captured some ethernet frames  with a digital oscilloscope 
> and we analyze then with matlab to have a real vision of the 
> standard 
> because in the 802.3 standard you cannot find all the information 
> you 
> need. If you want the frame captures and the matlab program or if 
> you 
> have any question about the standard please write me 
> 
>  My email is: javier_castillo_villar@y...  
> 
> 
> ----- Original Message ----- 
> From: "Igor Mohor" <igorm@o... > 
> To: <ethmac@o... > 
> Date: Wed, 17 Apr 2002 01:57:00 +0200 
> Subject: RE: [ethmac] Standard info. 
> 
> > 
> > 
> > Try reading the spec. I wrote ;) 
> > 
> > > -----Original Message----- 
> > > From: owner-ethmac@o... 
> > 
> [/cgi-bin/post.cgi?cmd=new&to=owner-ethmac%20at%20opencores% 
> 20dot%20org&msg=/ml-archive/ethmac/msg00035.shtml 
> > > Behalf Of Wilson Roger 
> > > Sent: 16. april 2002 12:04 
> > > To: Open Cores - Ethernet (E-mail) 
> > > Subject: [ethmac] Standard info. 
> > > 
> > > 
> > > In order to understand how the core works I need to know 
> more 
> > > information about Ethernet itself. Can you suggest what 
> the 
> > best 
> > > sources of information are, the standard itself perhaps? 
> > > 
> > > Thanks. 
> > > 
> > > Roger. 
> > > 
> > > 
> > > 
> > > -- 
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> > 
> 
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