Re: [ethmac] =?gb2312?B?aGVscA==?=

[Javier_castillo_villar@yahoo.es]

 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�s 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�s longer than 1500 bytes it�s 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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