RE: [ethmac] help

["Igor Mohor" <igorm@opencores.org>]

IEEE802.3 says that the max size of the packet is 1518 bytes
(6 bytes dest. address +
 6 bytes source address +
 2 bytes length/type +
 46-1500 bytes of data

> -----Original Message-----
> From: owner-ethmac@opencores.org [mailto:owner-ethmac@opencores.org]On
> Behalf Of aramisp@yahoo.com
> Sent: 15. november 2002 20:22
> To: ethmac@opencores.org
> Subject: Re: [ethmac] help
>
>
>
> Why is the max size of a frame 1500 bytes.  Where is this number
> determined from. ???????
> (or aprox. 1500 bytes)
>
> ----- Original Message -----
> From: Javier_castillo_villar@y...
> To: ethmac@o...
> Date: Tue, 23 Apr 2002 11:17:52 +0200
> Subject: Re: [ethmac] =?gb2312?B?aGVscA==?=
>
> >
> >
> >  You can have various cases. If you are using DIX ethernet standard
> > (the windows standard) your length field are not the length of the
> > frame, it磗 the type of the frame, if you are using IP over
> > ethernet this
> > field is 0x800 if you are using ARP is 0x806. If you are using
> > 802.3 the
> > length type can be lower than the total length of the frame. This
> > is
> > because the frame are very short and the tx make padding that is
> > they
> > put character 0x20 to make the frame at least 64 bytes long.
> >  If in your trasmitter the frame it磗 longer than 1500 bytes it磗
> > an error
> > because the IP must know the MTU(maximun transfer unit) of the phy
> > layer and he must send only the number of bytes that the phy layer
> > can
> > send.
> >
> >
> >
> >
> >
> > ----- Original Message -----
> > From: "lxn" <panic@1... >
> > To: ethmac@o...
> > Date: Thu, 18 Apr 2002 20:31:05 +0800 (CST)
> > Subject: [ethmac] =?gb2312?B?aGVscA==?=
> >
> > > Hi,
> > > when the tx module sending out frames, if the number of length
> > > field is smaller than the real frame size, what shall i do?
> > Cut the
> > > frame to meet the length field or transmit the whole frame?
> > And is
> > > this considered a error?
> > >
> > >
> >
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