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<DIV><SPAN class=052514508-17022004><FONT face=Arial color=#0000ff size=2>1.
Yes, 60 bytes is min and the driver pads with NUL bytes.</FONT></SPAN></DIV>
<DIV><SPAN class=052514508-17022004><FONT face=Arial color=#0000ff
size=2> Does Ethereal really show the length of the ethernet frame
or just the length of the received</FONT></SPAN></DIV>
<DIV><SPAN class=052514508-17022004><FONT face=Arial color=#0000ff
size=2> IP packet?</FONT></SPAN></DIV>
<DIV><SPAN class=052514508-17022004><FONT face=Arial color=#0000ff size=2>2. The
extra spaces are the padding done by the transmitting host to make if >60
bytes.</FONT></SPAN></DIV>
<DIV><SPAN class=052514508-17022004><FONT face=Arial color=#0000ff
size=2> This padding is not shown in the IP header but only in
the ethernet frame, of course.</FONT></SPAN></DIV>
<DIV><SPAN class=052514508-17022004><FONT face=Arial color=#0000ff
size=2></FONT></SPAN> </DIV>
<DIV><SPAN class=052514508-17022004><FONT face=Arial color=#0000ff size=2>So
things are probably quite normal.</FONT></SPAN></DIV>
<DIV><SPAN class=052514508-17022004><FONT face=Arial color=#0000ff
size=2></FONT></SPAN> </DIV>
<DIV><SPAN class=052514508-17022004><FONT face=Arial color=#0000ff
size=2>rgds</FONT></SPAN></DIV>
<DIV><SPAN class=052514508-17022004><FONT face=Arial color=#0000ff
size=2>bengan</FONT></SPAN></DIV>
<DIV><SPAN class=052514508-17022004><FONT face=Arial color=#0000ff
size=2></FONT></SPAN> </DIV>
<BLOCKQUOTE>
<DIV class=OutlookMessageHeader dir=ltr align=left><FONT face=Tahoma
size=2>-----Original Message-----<BR><B>From:</B>
en-nut-discussion-bounces@egnite.de
[mailto:en-nut-discussion-bounces@egnite.de]<B>On Behalf Of
</B>HeltonGA@aol.com<BR><B>Sent:</B> den 17 februari 2004 06:37<BR><B>To:</B>
en-nut-discussion@egnite.de<BR><B>Subject:</B> [En-Nut-Discussion] Ethereal -
RTL8019AS data length mismatch<BR><BR></FONT></DIV><FONT
face=arial,helvetica><FONT lang=0 face=Arial size=2 FAMILY="SANSSERIF"
PTSIZE="10">I am a bit confused about some results that I'm seeing in message
lengths captured. Using Ethereal to capture traffic, I try to establish a TCP
connection using SuperScan4.0. Ethereal reports a TCP message that is 54 bytes
("54 bytes on wire, 54 bytes captured") in length with SYN bit set, Seq Num
xxxx, yada, yada, yada. Anyway - why is the message length 54 bytes ? Isn't
the minimum message length supposed to be 60 bytes for Ethernet ?<BR><BR>Now
on to the RTL8019AS. I captured this same message on my development board.
When I read the message length from the message header, it is 64 bytes.
Subtract out the 4 bytes for the CRC and there are 60 data bytes. Just what I
would have expected. When I read out the 60 bytes from the RTL8019 and buffer
them, there are 54 bytes that comprise the Ethernet Header, IP Header, and TCP
Header (14 + 20 + 20) plus 6 space characters (0x20).<BR><BR>Why is there an
apparent mismatch in data lengths ? Is Ethereal just ignoring the extra
space characters or is the RTL8019 making them up ?<BR><BR>By the way, the IP
Total Length field is (40). This would account for the IP Header and TCP
Header, but would not account for any "extra" spaces (pads) appended as TCP
data.<BR><BR>Does anyone know what's going on here ?<BR><BR>Thanks in
advance.<BR>Fiz</FONT> </FONT></BLOCKQUOTE></BODY></HTML>